NumberADay

206

2012-01-27T03:00:00.000-05:00

206 = 2 x 103.

206 is the smallest number m such that 111¹¹¹ + m is prime.

The squares of 206 and 208, two consecutive even numbers, use the same digits: 206² = 42436 and 208² = 43264.

206 = 1³ + 2³ + 2³ + 4³ + 5³.

206 is 248 in base 9.

206 is the smallest number whose English name (two hundred and six) contains all five vowels exactly once.

Source: Number Gossip

652

2012-01-26T03:00:00.000-05:00

652 = 2² x 163. It is a power of 2 written backwards.

652 has a unique representation as a sum of three squares: 652 = 2² + 18² + 18².

652 is the maximum number of regions into which 26 circles can divide the plane.

652 is the only known non-perfect number whose number of divisors and sum of smaller divisors are perfect.

652 is 220011 in base 3. It is 543 in base 11, 464 in base 12, and 246 in base 18.

Source: What's Special About This Number?

9797

2012-01-25T03:00:00.000-05:00

9797 = 97 x 101. It is the product of two consecutive primes.

The square root of 9797 includes the digits 9797 immediately to the right of the decimal point: 98.979795918 . . .

9797 has two representations as a sum of two squares: 9797 = 31² + 94² = 49² + 86².

9797 is the hypotenuse of two primitive Pythagorean triples: 9797² = 4995² + 8428² = 5828² + 7875².

9797 is a divisor of 91¹² - 1.

The sum of the digits of 9797 is eight times the number of digits: 9 + 7 + 9 + 7 = 8 x 4 = 32.

9797 is IBM in base 23.

Source: What's Special About This Number?

941

2012-01-24T03:00:00.000-05:00

941 is a prime number.

941 has a representation as a sum of two squares: 941 = 10² + 29².

941 is the hypotenuse of a primitive Pythagorean triple: 941² = 580² + 741².

941 is the smallest prime formed by the reverse concatenation of three consecutive squares.

941 is the smallest number whose proper substrings sum to its reversal: 9 + 4 + 1 + 94 + 41 = 149.

941 is the smallest prime resulting from the nine-digit fraction equation (A + B)^C + (D + E)^F + (G + H)^I, where the letters A through I represent any combination of the nine digits 1 through 9. Note that (4 + 5)³ + (6 + 8)² + (7 + 9)¹ is the only distinct solution for 941.

Source: Prime Curios!

737

2012-01-23T03:00:00.000-05:00

737 = 11 x 67.

737 is the smallest multidigit number m such that m^m+ 2 is prime.

737 is 515 in base 12 and 191 in base 21.

737 is the sum of two positive cubes: 737 = 9³ + 2³.

The Boeing 737 is a twin-engine, narrow-body jet airliner that first flew in 1967.

Source: Prime Curios!

358

2012-01-20T03:00:00.000-05:00

358 = 2 x 179.

358 is the smallest number whose first two digits are distinct odd primes such that their sum equals the third digit.

The sum of the digit splits of 358 is equal to the product of the digits of 358: (3 + 58) + (35 + 8) + (3 + 5 + 8) = 120 = 3 x 5 x 8.

358 has a base 3 representation (111021) that ends with its base 7 representation (1021).

358 is the sum of six consecutive primes: 358 = 47 + 53 + 59 + 61 + 67 + 71.

The Jaguar XJ X358 is a luxury car that debuted in 2007.

Source: Prime Curios!

278

2012-01-19T03:00:00.000-05:00

278 = 2 x 139.

278 is the sum of the first 18 nonprimes.

278 has the representation 2⁸ + 22.

278 is the closest integer to 6^π.

278 is 545 in base 7.

Telephone area code 278 serves Ann Arbor, Michigan, and the surrounding area.

Source: What's Special About This Number?

636

2012-01-18T03:00:00.000-05:00

636 = 2² x 3 x 53.

The decimal part of the fifth root of 636 begins with the digits 636.

636 is 336 in base 14.

636 is the sum of 10 consecutive primes: 636 = 43 + 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79 + 83.

Telephone area code 636 serves the east-central portion of the state of Missouri.

Source: What's Special About This Number?

4393

2012-01-17T03:00:00.000-05:00

4393 = 23 x 191.

4393 is 1000100101001 in base 2 (binary).

4393 is a number such that each digit leaves the same nonzero remainder when each is divided into the number.

4393 is a multiple of 23 such that reversing the digits and subtracting 1 gives a result that is also a multiple of 23.

4393 is the sum of distinct 5th powers: 4393 = 5⁵ + 4⁵ + 3⁵ + 1⁵.

Parlophone recording R. 4393 featured the song "No Other Baby" by The Vipers, later recorded by Paul McCartney.

Source: On-Line Encyclopedia of Integer Sequences

438

2012-01-13T03:00:00.000-05:00

438 = 2 x 3 x 73.

438 is a Smith number because the sum of its digits is equal to the sum of the digits of its prime factors: 4 + 3 + 8 = 2 + 3 + 7 + 3 = 15.

438 is 110110110 in base 2 (binary) and 666 in base 8. It is 3223 in base 5 and 141 in base 19.

438 divides 65⁶ - 1.

438 is the sum of 10 positive 5th powers: 438 = 3⁵ + 2⁵ + 2⁵ + 2⁵ + 2⁵ + 2⁵ + 2⁵ + 1⁵ + 1⁵ + 1⁵.

The term "438 match" or "438 game" has been used by cricket news media to describe the famous 2006 One Day International in which Australia scored a world record 434 in their innings, only to see South Africa respond in their innings with 438.

Source: What's Special About This Number?

724

2012-01-12T03:00:00.000-05:00

724 = 2² x 181.

724 has a representation as a sum of two squares: 724 = 18² + 20².

724 divides 19⁴ - 1.

724 is the number of perfect connected undirected simple graphs on seven nodes.

724 is the number of different arrangements of 10 non-attacking queens on a 10 x 10 chessboard.

724 Hapag is an asteroid discovered in 1911, lost, then rediscovered in 1988.

Source: What's Special About This Number?

1293

2012-01-11T03:00:00.000-05:00

1293 = 3 x 431.

The sum of the divisors of 1293 is a cube: 1 + 3 + 431 + 1293 = 1728 = 12³.

1293 is a divisor of 26¹⁰ - 1.

1293 is a structured truncated tetrahedral number.

1293³ = 2161700757 is the sum of three consecutive primes: 2161700757 = 720566909 + 720566921 + 720566927.

Southern Pacific 1293 is a retired switch engine built in 1924 and now on display in Tracy, California.

Source: What's Special About This Number?

1126

2012-01-10T03:00:00.000-05:00

1126 = 2 x 563.

1126 is the number of 3 x 4 checkerboards in which the set of red squares is edge-connected.

1126 is the sum of the first 15 Sophie Germain primes.

1126³ (1427628376) includes the digits of 1126² (1267876).

In the year 1126, Adelard of Bath translated Muhammad ibn-Musa al-Kwarizmi's arithmetic and astronomical tables into Latin.

Source: On-Line Encyclopedia of Integer Sequences

826

2012-01-09T03:00:00.000-05:00

826 = 2 x 7 x 59.

826 is the sum of seven positive 5th powers: 826 = 3⁵ + 3⁵ + 3⁵ + 2⁵ + 2⁵ + 2⁵ + 1⁵.

The sum of the digits of the 826th prime (6343) equals the sum of the digits of 826: 6 + 3 + 4 + 3 = 8 + 2 + 6 = 16.

The digits of 826² (68276) contain the digits of 826 as a subsequence.

826 National is a nonprofit organization that manages a network of writing and tutoring centers.

Source: On-Line Encyclopedia of Integer Sequences

423

2012-01-06T06:00:00.000-05:00

423 = 3² x 47.

423 is a number that does not have any digits in common with its cube (75686967).

423 is the sum of 13 consecutive primes: 423 = 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53 + 59.

Inserting the digit 1 between adjacent digits of 423 produces a prime: 41213.

423 Diotima is one of the largest main-belt asteroids.

Source: What's Special About This Number?

537

2012-01-05T06:00:00.000-05:00

537 = 3 x 179.

537 divides the sum of the cubes of the first 537 primes.

537 is 656 in base 9.

The sum of the digits of 537 is 5 times the number of digits: 5 + 3 + 7 = 5 x 3 = 15.

537 is the average of three successive primes: 537 = (523 + 541 + 547)/3.

In the final official count in the 2000 U.S. presidential election, George W. Bush defeated Al Gore by 537 votes in the state of Florida.

Source: What's Special About This Number?

816

2012-01-04T06:00:00.000-05:00

816 = 2⁴ x 3 x 17.

816 is the 16th tetrahedral number.

816/(8 x 1 x 6) = 816/48 = 17, a prime. 816 is the largest three-digit integer that has this property.

816 is 30300 in base 4 and 330 in base 16. It is 2244 in base 7 and 424 in base 14.

816 is a telephone area code that covers the Kansas City area in Missouri.

Source: Prime Curios!

124

2012-01-03T06:00:00.001-05:00

124 = 2² x 31.

124 is 444 in base 5.

124 is the smallest number whose sum of digits (1 + 2 + 4 = 7) as well as the number itself are one less than the cube of a prime.

124 is the smallest number with the property that its first three multiples contain the digit 2: 124, 248, and 372.

124 is the sum of eight consecutive primes: 124 = 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29.

124 = 2⁷ - 2².

124 = 5² + 5² + 5² + 7².

The Fiat 124 was a family car produced in Italy from 1966 to 1974.

Source: Prime Curios!

2012

2011-12-23T06:00:00.000-05:00

2012 = 2² x 503.

2012, 2013, 2014, and 2015 are each the product of three prime numbers.

2012! has a square number of digits (5776 = 76²).

2012² = 4048144 and 4418404 = 2102².

2012 and its square (4048144) use only the digits 0, 1, 2, 4, and 8.

2012 is a year in which there are five Wednesdays in the month of February.

2012 is a blue moon year.

The end of the "longest period" (Long Count) Mayan calendar known to exist is said to be December 21, 2012.

2012 is the 100th anniversary of the sinking of the RMS Titanic. It is also the centennial of the birth of Alan Turing.

Source: On-Line Encyclopedia of Integer Sequences

524

2011-12-22T06:00:00.001-05:00

524 = 2² x 131.

524 is a divisor of 53⁵ - 1.

6 x 7 x 9 x 524 x 831 = 164,597,832 uses each of the digits from 1 to 9 once on both sides of the equality.

524 is 201102 (palindromic) in base 3.

The USS Pickerel (USN-524) was a submarine commissioned in 1949.

Source: Positive Integers

1011

2011-12-21T06:00:00.002-05:00

1011 = 3 x 337.

1011 is the smallest number without trailing zeroes such that the reversal of its cube is the cube of a different number (1101).

1011 has a square that is formed by inserting three 2s into it: 1011² = 1022121.

1011 is 323 (palindromic) in base 18. 1011 has a representation ending in 3 in base 4, 6, 7, 8, 9, 12, 14, and 18.

The Nokia 1011 was the first mass-produced GSM phone.

Source: Number Gossip

107

2011-12-20T06:00:00.000-05:00

107 is a prime number.

107 is 1101011 in base 2 (binary).

107 and 109 form a twin prime pair.

2¹⁰⁷ - 1 is a Mersenne prime.

107 is the smallest three-digit prime that remains a prime when 2 is added to any one of its digits: 307, 127, and 109 are all primes.

107 is the maximum number of steps that a four-state Turing machine can make on an initially blank tape before it halts.

107 Camilla is one of the largest main-belt asteroids.

Source: Prime Curios!

383

2011-12-19T06:00:00.002-05:00

383 is a prime number. It is a sexy prime because 383 + 6 = 389 is also prime.

383 is the only known multidigit palindromic Woodall prime.

383 is the sum of the first three three-digit palindromic primes: 383 = 101 + 131 + 151.

383 is the smallest prime that can be represented by the sum of a prime and its reversal: 383 = 241 + 142.

383 is a divisor of the Mersenne number 2¹⁹¹ - 1.

The Chevy 383 stroker engine uses an altered crankshaft to increase the stroke of the pistons.

Source: Prime Curios!

967

2011-12-16T06:00:00.002-05:00

967 is a prime number. 967 in reverse is the prime 769.

967 is a divisor of 97⁷ - 1.

967 is the number of six-digit triangular numbers.

967 is 595 in base 13.

967 millimeters is the record for annual rainfall in Melbourne, Australia, set in 1916.

Source: Prime Curios!

743

2011-12-15T06:00:00.003-05:00

743 is a prime number. It is a Sophie Germain prime because 2 x 743 + 1 = 1487 is a prime.

743 is the number of independent sets of the graph of the tesseract (four-dimensional cube).

648⁷ + 139968⁴ = 7558272³.

743 is 616 in base 11 and 212 in base 19.

The sun's mass is about 743 times the combined mass of all the planets in the solar system.

Source: Number Gossip

1352

2011-12-14T06:00:00.002-05:00

1352 = 2³ x 13².

1352 has two representations as a sum of two squares: 1352 = 14² + 34² = 26² + 26².

1352 is a divisor of 99⁴ - 1.

1352 is a hexagonal prism number.

1352 is 20402 in base 5 and 242 in base 25. It is 800 in base 13 and 200 in base 26.

NGC 1352 is a barred spiral galaxy in the constellation Eridanus.

Source: What's Special About This Number?

197

2011-12-13T06:00:00.001-05:00

197 is a prime number.

197 is a centered heptagonal number.

197 is the sum of the first 12 primes: 197 = 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37. It is also the smallest prime that is the sum of seven consecutive primes: 197 = 17 + 19 + 23 + 29 + 31 + 37 + 41.

197 is the sum of the digits of all two-digit primes.

197 is the sum of the squares of all composite digits: 197 = 4² + 6² + 8² + 9².

197 has a representation as a sum of two squares: 197 = 1² + 14².

197 and 199 form a twin prime pair.

197 is the hypotenuse of a primitive Pythagorean triple: 197² = 28² + 195².

The chemical element gold has one stable isotope, which has a total of 197 neutrons and protons in its nucleus.

Source: Prime Curios!

647

2011-12-12T06:00:00.002-05:00

647 is a prime number.

647 is a divisor of 43¹⁷ - 1.

647 is the smallest prime that can be written as 2a² - 1 and as 3b³ - 1.

647 is 343 in base 14.

647 is the sum of five consecutive primes: 647 = 113 + 127 + 131 + 137 + 139.

Tremont 647 is a restaurant in Boston.

Source: Prime Curios!

286

2011-12-09T06:00:00.004-05:00

286 = 2 x 11 x 13.

286 is the 11th tetrahedral number.

286 is a heptagonal number.

286 is the number of rooted trees with 9 vertices.

286 is 2121 in base 5 and 141 in base 15.

286 is the shorthand for the Intel 80286 microprocessor chip.

Source: What's Special About This Number?

360

2011-12-08T06:00:00.002-05:00

360 = 2³ x 3² x 5.

360 has a representation as a sum of two squares: 360 = 6² + 18².

360 is the largest number out of two (the other being 36) that have the same number of letters in its Roman numeral representation (CCCLX) as its double (DCCXX), triple (MLXXX), quadruple (MCDXL), quintuple (MDCCC), sextuple (MMCLX), and septuple (MMDXX).

360 is the smallest number divisible by every natural number from 1 to 10 except 7.

One of the divisors of 360 is 72, which is the number of prime numbers less than 360.

360 is the sum to two twin primes: 360 = 179 + 181.

360 is the number of degrees in a circle.

Source: Number Gossip

939

2011-12-07T06:00:00.002-05:00

939 = 3 x 313.

939 is a divisor of 25⁴ - 1.

939 has a cube root whose decimal part starts with the digits 1 to 9 in some order: 9.792386145. . .

939 is 32223 in base 4 and 12224 in base 5.

939 is a number n such that n - 2 and n + 2 are consecutive primes: 937 and 941.

The Berklee College of Music's Cafe 939 is a student-run music venue and coffeehouse.

Source: What's Special About This Number?

175

2011-12-06T06:00:00.002-05:00

175 = 5² x 7.

175 is a divisor of 76² - 1.

175 is a decagonal number.

175 = 1¹ + 7² + 5³.

175 is the smallest number n such that n⁶ + 6 is prime.

Emory University was 175 years old in the year 2o11.

Source: Prime Curios!

831

2011-12-05T06:00:00.003-05:00

831 = 3 x 277.

6 x 7 x 9 x 524 x 831 = 164,597,832 (using each of the nine digits 1 to 9 on both sides of the equality).

831 is a divisor of 35¹² - 1.

831 is 11311 in base 5 and 696 in base 11.

831 is the sum of 12 positive fifth powers: 831 = 3⁵ + 3⁵ + 3⁵ + 2⁵ + 2⁵ + 2⁵ + 1⁵ + 1⁵ + 1⁵ + 1⁵ + 1⁵ + 1⁵.

831 stands for "I love you": eight letters, three words, one meaning.

Source: Numeropedia

342

2011-12-02T06:00:00.003-05:00

342 = 2 x 3² x 19.

342 is 666 in base 7. It is the smallest number that can be represented by 666 in any base. 342 is also 2332 in base 5.

342 is a heptagonal number.

342 is the number of inequivalent binary linear codes of length 8.

IC 342 (also known as Caldwell 5) is a spiral galaxy in the constellation Camelopardalis.

Source: Number Gossip

727

2011-12-01T06:00:00.002-05:00

727 is a prime number.

727 is the smallest prime of the form n³ - 2.

727 = 1! + (1 + 2)! + (1 + 2 + 3)!

727 is the smallest odd prime that can be represented as the sum of a cube and its reversal: 727 = 8³ + 215 = 512 + 215.

727 is the first prime whose square (528529) can be represented as the concatenation of two consecutive numbers.

The Boeing 727 was the first three-engine jet built for commercial service.

Source: Number Gossip

1226

2011-11-30T06:00:00.000-05:00

1226 = 2 x 613.

1226 has a representation as a sum of two squares: 1226 = 1² + 35².

1226 is 14401 in base 5 and 3401 in base 7.

1226 is a divisor of 65³ - 1.

1226 is a central polygonal number (lazy caterer's sequence), or the maximum number of pieces formed when slicing a pancake with 49 cuts.

The Stone Circles of Senegambia is site 1226 on the UNESCO World Heritage list.

Source: On-Line Encyclopedia of Integer Sequences

147

2011-11-29T06:00:00.002-05:00

147 = 3 x 7².

147 is the number of one-sided 6-polyhexes.

147 = 14² - 7² = (14 + 7)7.

147(14 + 7) = 14³ + 7³ = 3087.

147 is 300 in base 7, 77 in base 20, and 70 in base 21. It is 2103 in base 4, 403 in base 6, and 103 in base 12 (and 93 in base 16, 83 in base 18, and 63 in base 24).

The binary form of 147 (10010011) contains all two-digit binary numbers (00, 01, 10, and 11) in a sequence.

The digits forming 147 also form the left-hand column of a normal decimal keypad.

Source: What's Special About This Number?

619

2011-11-28T06:00:00.003-05:00

619 is a prime number.

617 and 619 form a twin prime pair.

619 = 6! - 5! + 4! - 3! + 2! - 1!

619 is the only strobogrammatic prime with distinct digits. It is the smallest strobogrammatic prime that is not a palindrome.

Nova 619 is a webcomic.

Source: Prime Curios!

834

2011-11-23T06:00:00.003-05:00

834 = 2 x 3 x 139.

834 is a divisor of 43⁶ - 1.

834 is a cake number. 834 is the maximum number of regions into which 17 cuts can divide a cube.

834 is the sum of six consecutive primes: 834 = 127 + 131 + 137 + 139 + 149 + 151.

The Volvo PV834 was one of a series of commercial vehicles, including ambulances, produced in the 1950s.

Source: Number Gossip

132

2011-11-22T06:00:00.003-05:00

132 = 2² x 3 x 11.

The sum of all two-digit numbers that you can make from 132 is 132: 12 + 13 + 21 + 23 + 31 + 32 = 132. It is the smallest number with this property.

132 is the sixth Catalan number.

132 is a divisor of 23² - 1.

The game board for Indian snakes and ladders (Moksha Patamu) has 132 squares.

Source: Number Gossip

225

2011-11-21T06:00:00.005-05:00

225 = 3² x 5².

225 = 15². 225 is the smallest square that starts with two identical digits.

225 is the smallest square whose external digits (25) form a square, and whose internal digits (2) form a prime.

225 is the only three-digit square with all prime digits.

225 has a representation as a sum of two squares: 225 = 9² + 12².

225 is a divisor of 26² - 1.

225 is an octagonal number. It is also a centered octagonal number.

A Scrabble board has 225 squares.

Source: Number Gossip

928

2011-11-18T06:00:00.003-05:00

928 = 2⁵ x 29.

928 has a representation as a sum of two squares: 928 = 12² + 28².

928 is the sum of four consecutive primes: 928 = 227 + 229 + 233 + 239. It is also the sum of eight consecutive primes: 928 = 101 + 103 + 107 + 109 + 113 + 127 + 131 + 137.

928 is the sum of six positive cubes in exactly three ways.

928 is the number of ways to toss a coin 10 times and not get a run of six.

The Porsche 928 was a sports car produced from 1978 to 1995.

Source: Wikipedia

1068

2011-11-17T06:00:00.002-05:00

1068 = 2² x 3 x 89.

1068 has the representation 1068 = 2¹⁰ + 44.

1068 is a divisor of 55⁴ - 1.

1068 is the total number of parts in all partitions of 15.

1068 is an octadecagonal number.

NGC 1068 (also known as Messier 77) is a barred spiral galaxy about 47 million light-years away in the constellation Cetus.

Source: On-Line Encyclopedia of Integer Sequences

309

2011-11-16T06:00:00.002-05:00

309 = 3 x 103.

309 is a centered hendecagonal number.

309 is the smallest number whose fifth power (309⁵ = 2817036000549) is pandigital (contains every digit from 0 to 9 at least once).

309³ + 309⁰ + 309⁹ is a prime, with prime digital length.

309 is 373 in base 9. It is 621 in base 7 and 261 in base 11.

309 is a telephone area code serving the state of Illinois.

Source: Number Gossip

515

2011-11-15T06:00:00.002-05:00

515 = 5 x 103.

515 is the number of graphs on six vertices with no isolated vertices.

515 is 20003 in base 4 and 1003 in base 8. It is 203 in base 16.

515 is the sum of nine consecutive primes: 515 = 41 + 43 + 47 + 53 + 59 + 61 + 67 + 71 + 73.

In The Divine Comedy, Dante Alighieri wrote that the Apocalypse would be preceded by a messenger represented by the number "five hundred and ten and five" (515).

Source: What's Special About This Number?

904

2011-11-14T06:00:00.004-05:00

904 = 2³ x 113.

904 has a representation as a sum of two squares: 904 = 2² + 30².

904 is the maximum number of regions into which 42 lines divide the plane. It is a lazy caterer's number (central polygonal number) for 42 cuts.

904 has a cube that is the sum of three positive cubes.

904 is 12104 in base 5 and 4104 in base 6. It is 1214 in base 9, and it is 404 in base 15 and 323 in base 17.

The Porsche 904 was an automobile produced in 1964 and 1965.

Source: What's Special About This Number?

111111

2011-11-11T06:00:00.003-05:00

111111 = 3 x 7 x 11 x 13 x 37.

111111 is a divisor of 100³ - 1.

111111 has the representation 2² x 3⁴ x 7³ - 21.

The 111,111th triangular number is palindromic: 6,172,882,716. The 1111th triangular number (617,716) and the 11th triangular number (66) are also palindromic.

111111 x 111111 = 12345654321.

1 x 9 + 2 = 11

12 x 9 + 3 = 111

123 x 9 + 4 = 1111

1234 x 9 + 5 = 11111

12345 x 9 + 6 = 111111

3 x 37 = 111

33 x 3367 = 111111

3333 x 33336667 = 111111111111

Source: Prime Curios!

973

2011-11-10T06:00:00.002-05:00

973 = 7 x 139.

973 is 12343 in base 5. It is 4301 in base 6, 1301 in base 9, and 301 in base 18.

973 is the sum of five positive fifth powers: 973 = 3⁵ + 3⁵ + 3⁵ + 3⁵ + 1⁵.

973 is divisible by the sum of the squares of its digits: 9² + 7² + 3² = 139.

Mr. 973 is a hip hop performer based in New Jersey.

Source: Positive Intgers

567

2011-11-09T06:00:00.002-05:00

567 = 3⁴ x 7.

567 is the smallest possible sum of primes that are formed using all 10 digits: 567 = 401 + 89 + 67 + 5 + 3 + 2.

567 is the smallest number that together with its square (567² = 321489) uses the digits 1 to 9 exactly once.

567 is 4232 in base 5 and 2343 in base 6. It is 700 in base 9.

567 is a divisor of 26⁶ - 1.

The EMD 567 is a line a diesel engines produced by General Motors from 1938 until 1966 for locomotives.

Source: Number Gossip

968

2011-11-08T06:00:00.003-05:00

968 = 2³ x 11².

968 is an Achilles number. Each prime factor occurs with an exponent greater than 1, but the number itself is not a perfect power.

968 has a representation as a sum of two squares: 968 = 22² + 22².

968 is a divisor of 9⁵ - 1.

968 is 2552 in base 7 and 242 in base 21. It is 800 in base 11 and 200 in base 22.

The Porsche 968 was a sports car sold from 1992 to 1995.

Source: What's Special About This Number?

564

2011-11-07T06:00:00.001-05:00

564 = 2² x 3 x 47.

564 is the largest number that can be written with all the digits from 1 to 5 (without repetition) as a sum of primes in two ways: 564 = 541 + 23 = 523 + 41.

The largest prime factor of F₁₁ (the largest completely factored Fermat number) has 564 digits.

564 is 202220 in base 3 and 4224 in base 5. It is 1434 in base 7 and 686 in base 9. It is 345 in base 13 and 234 in base 16.

Interstate 564 (I-564), known as Admiral Taussig Boulevard, runs east for 3.03 miles, providing access to Naval Station Norfolk in Virginia.

Source: Prime Curios!

779

2011-11-04T06:00:00.002-04:00

779 = 19 x 41.

779 is a divisor of 83³ - 1.

779 is the sum of 11 consecutive primes: 779 = 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79 + 83 + + 89 + 97.

The sum of the digits of 779 equals the sum of the digits of the 779th prime (5927): 7 + 7 + 9 = 5 + 9 + 2 + 7 = 23.

779 yields a prime when 3 is either prefixed or appended: 3779 and 7793 are both primes.

Polaroid 779 was a high-speed color film for instant cameras.

Source: On-Line Encyclopedia of Integer Sequences

559

2011-11-03T06:00:00.003-04:00

559 = 13 x 43.

559 is a centered cube number.

559 is 202201 in base 3 and 20233 in base 4.

559 is the sum of five consecutive primes and seven consecutive primes: 559 = 103 + 107 + 109 + 113 + 127 = 67 + 71 + 73 + 79 + 83 + 89 + 97.

The German submarine U-559 sank in the Mediterranean Sea in 1942, but not before British sailors managed to recover key cryptographic material from the vessel.

Source: What's Special About This Number?

643

2011-11-02T06:00:00.002-04:00

643 is a prime number.

641 and 643 form a twin prime pair.

643 is the largest prime factor of 123456: 643(64³) = 123456.

643 = (3⁸ + 8³)/(3 + 8).

A record 643 millimeters of rain fell in Sydney, Australia, in the month of June 1950.

Source: Prime Curios!

345

2011-11-01T06:00:00.003-04:00

345 = 3 x 5 x 23.

345 * 2³⁴⁵ - 345 - 2³⁴⁵ is a prime number.

345 is 1333 in base 6 and 113 in base 18.

345 is the sum of three positive cubes: 345 = 7³ + 1³ + 1³.

345 is the local telephone area code for the Cayman Islands.

Source: Prime Curios!

1393

2011-10-31T06:00:00.002-04:00

1393 = 7 x 199.

1393 is a divisor of 92³ - 1.

1393 is an NSW number.

1393 is 4030 in base 7 and 717 in base 14.

1393 is the number of nodes in a regular 16-sided polygon with all diagonals drawn.

International Brotherhood of Electrical Workers Local Union 1393 in based in Indianapolis, Indiana.

Source: What's Special About This Number?

768

2011-10-28T06:00:00.002-04:00

768 = 2⁸ x 3.

768 has a unique representation as a sum of three squares: 768 = 16² + 16² + 16².

768 is a divisor of 65⁴ - 1.

768 is the number of subsets of {1, 2, 3, . . . , 12} that have an integer average.

416,768 = 768² - 416².

RSA-768 was a member of set of large semiprimes (RSA Numbers) that were part of the RSA Factoring Challenge.

Source: What's Special About This Number?

273

2011-10-27T06:00:00.002-04:00

273 = 3 x 7 x 13.

273 is 100010001 in base 2 (binary), 333 in base 9, and 111 in base 16.

The 273rd prime minus the sum of gaps between the first 273 consecutive primes minus 1 equals 273.

273 is the sum of each of two consecutive sums of consecutive numbers: 273 = 36 + 37 + 38 + 39 + 40 + 41 + 42 = 43 + 44 + 45 + 46 + 47 + 48.

The zero on the Celsius temperature is 273 (to the nearest whole number) on the Kelvin temperature scale.

Source: Prime Curios!

762

2011-10-26T06:00:00.002-04:00

762 = 2 x 3 x 127.

It is a Smith number because the sum its digits is equal to the sum of the digits of its prime factors: 7 + 6 + 2 = 2 + 3 + 1 + 2 + 7 = 15.

762 is the starting location of the string 999999 in the decimal expansion of pi. This is known as the Feynman point.

762 is the sum of four consecutive primes: 762 = 181 + 191 + 193 + 197.

762 is a divisor of 19³ - 1.

USS Columbus (SSN-762) was a submarine in the U.S. Navy, launched in 1992.

Source: What's Special About This Number?

540

2011-10-25T06:00:00.003-04:00

540 = 2² x 3³ x 5. All prime divisors are consecutive primes starting at 2.

540 is a heptagonal number and a decagonal number.

540 is divisible by its reverse, 45.

540 is the sum of three distinct positive cubes: 540 = 8³ + 3³ + 1³.

540 is the sum of the internal angles of a five-sided convex polygon (or a pentagon).

Source: What's Special About This Number?

1179

2011-10-24T06:00:00.003-04:00

1179 = 3² x 131.

1179 is the sum of the squares of three consecutive primes: 1179 = 17² + 19² + 23².

1179 and 1179² (1390041) have the same digit sum: 1 + 1 + 7 + 9 = 1 + 3 + 9 + 0 + 0 + 4 + 1 = 18.

1179 is a divisor of 53¹⁰ - 1.

1179 is 2233 in base 8.

NGC 1179 is a barred spiral galaxy in the constellation Eridanus.

Source: On-Line Encyclopedia of Integer Sequences

3278

2011-10-21T06:00:00.003-04:00

3278 = 2 x 11 x 149. The three prime factors are distinct in length.

3278²⁴ + 1 is a prime number.

The decimal expansion of pi has a string of two 7s starting in the 3278th position.

In base 6, the digits of 3278 are, in order, the first five digits of the periodic sequence with initial period 2, 3, 1, 0: 23102.

The IBM 3278 was a member of a class of video terminals (display devices) manufactured in the 1970s.

Source: On-Line Encyclopedia of Integer Sequences

324

2011-10-20T06:00:00.003-04:00

324 = 2² x 3⁴.

324 is a perfect square: 324 = 18².

324 is the smallest untouchable square. Untouchable numbers are those that are not the sum of the proper divisors of any number.

324 is the largest possible product of positive integers with sum 16.

324 Bamberga, discovered in 1892, is one of the largest asteroids in the main belt.

Source: Number Gossip

418

2011-10-19T06:00:00.003-04:00

418 = 2 x 11 x 19.

418 has the property that the sum of its prime factors is equal to the product of its digits: 2 + 11 + 19 = 4 x 1 x 8 = 32.

418 is the sum of three nonzero fourth powers: 418 = 4⁴ + 3⁴ + 3⁴.

418 is 262 in base 13.

418 is a telephone area code in the province of Quebec, Canada.

Source: What's Special About This Number?

924

2011-10-18T06:00:00.004-04:00

924 = 2² x 3 x 7 x 11.

924 is the smallest value of n such that 2n choose n is divisible by n²: 1848 choose 924 is divisible by 924².

924 is the sixth central binomial coefficient.

924 is 1110011100 in base 2 (binary).

924 is a divisor of 43² - 1.

The Porsche 924 was an automobile produced from 1976 t0 1988.

Source: Number Gossip

1136

2011-10-17T06:00:00.003-04:00

1136 = 2⁴ x 71.

1136 is a divisor of 17¹⁰ - 1.

1136 is a member of the toothpick sequence starting from a cross formed from four toothpicks.

1136 is the number of ways of writing 4 as a sum of eight squares.

1136 is the smallest number whose sum of squares of digits is 47: 1² + 1² + 3² + 6² = 47.

Spanish mathematician and astronomer Abraham bar Hiyya Ha-Nasi (Savasorda) died in the year 1136.

Source: On-Line Encyclopedia of Integer Sequences

613

2011-10-14T06:00:00.004-04:00

613 is a prime number.

613 is a centered square number.

613 is the smallest prime such that bringing the first digit to the back produces a triangular number (136) and repeating this operation produces a square (361).

613 is the smallest number n such that the numbers of divisors of n, n + 1, n + 2, and n + 3 are k, 2k, 4k, and 8k for k = 2.

613 has a representation as a sum of two squares: 613 = 17² + 18².

613 is the hypotenuse of a primitive Pythagorean triple: 613² = 35² + 612².

The 613 commandments (613 Mitzvot) is a numbering of the statements and principles of law, ethics, and spiritual practice contained in the Torah (the Five Books of Moses).

Source: Number Gossip

1029

2011-10-13T06:00:00.002-04:00

1029 = 3 x 7³.

1029 is the smallest order for which there are 19 groups.

1029 is 4433 in base 6, 3000 in base 7, and 333 in base 18. It can be written from base 2 to base 18 using only the digits from 0 to 9.

The sum of the base 2 digits (10000000101) of 1029 equals the sum of the base 4 digits (100011) of 1029.

1029 is the sum of distinct powers of 4: 1029 = 4⁵ + 4¹ + 4⁰.

The Atari 1029 printer was one of Atari's final printers for the XL series computers in 1984.

Source: What's Special About This Number?

108

2011-10-12T06:00:00.001-04:00

108 = 2² x 3³. It is the product of the first three numbers raised to themselves: 108 = 1¹ x 2² x 3³.

108 is the smallest number whose divisors contain every digit at least once. The divisors are: 1, 2, 3, 4, 6, 9, 12, 18, 27, 36, 54, 108.

108 is 99 in base 11.

The interior angles of a regular (equilateral) pentagon measure 108 degrees each.

There are 108 different types of heptomino, a shape made by fitting together seven squares.

For an article on the symbolism of 108, see the webpage "Why 108."

Source: Number Gossip

505

2011-10-11T06:00:00.002-04:00

505 = 5 x 101.

505 has two representations as a sum of two squares: 505 = 8² + 21² = 12² + 19².

505 is the hypotenuse of two primitive Pythagorean triples: 505² = 217² + 456² = 336² + 377².

505³ = 59³ + 163³ + 499³, where 59, 163, and 499 are primes.

505 is the magic constant for a 10 x 10 normal magic square.

505 is the model number of a type of denim jeans produced by Levi Strauss & Co.

Source: Prime Curios!

196

2011-10-07T06:00:00.005-04:00

196 = 2² x 7².

196 is the smallest square that contains a multidigit prime number as a substring.

196 = 14² is a perfect square.

196 is the difference of two square numbers: 196 = 50² - 48².

The consecutive squares 13² = 169 and 14² = 196 use the same digits; 31² = 961 also uses the same digits.

196 has a unique representation as a sum of three squares: 196 = 4² + 6² + 12².

196 is a pentagonal pyramidal number and a heptagonal pyramidal number.

It is conjectured that 196 is the lowest Lychrel number. It is the lowest number not known to produce a palindrome by repeated reversal and addition. The algorithm has been tested to more than 246 million digits without finding a palindrome, but no one has ever proved that it will never produce one.

The Mercedes-Benz W196 was an entry in the 1954 and 1955 Formula One car racing series, winning 9 of 12 races.

Source: Number Gossip

482

2011-10-06T06:00:00.002-04:00

482 = 2 x 241.

482 has a representation as a sum of two squares: 482 = 11² + 19².

482 is 222 in base 15. It is 585 in base 9.

482 is a number whose square (232,324) and cube (111,980,168) use different digits.

482 Music is an independent record label featuring international jazz.

Source: What's Special About This Number?

981

2011-10-05T06:00:00.002-04:00

981 = 3² x 109.

981 has a representation as a sum of two squares: 981 = 9² + 30².

327 + 654 = 981 uses each of the digits 1-9 once.

981 and 981² = 962,361 have the same initial digit and final digit.

Turkish Airlines Flight 981 was a McDonnell Douglas DC-10 that crashed in France in 1974, killing all 346 people on board.

Source: Numeropedia

186

2011-10-04T06:00:00.003-04:00

186 = 2 x 3 x 31.

186 is the maximum number of regions into which 9 spheres divide space.

7 x 5 x 3 x 2 - 4 x 3 x 2 x 1 = 186.

186 x 39 = 7254 uses each of the nine digits 1-9 once.

186 is 1221 in base 5 and 272 in base 8.

186 is the number of odd days in a year that is not a leap year.

Source: Number Gossip

594

2011-10-03T06:00:00.002-04:00

594 = 2 x 3³ x 11.

594 is 1001010010 in base 2 (binary). It is 4334 in base 5 and 1122 in base 8.

594 is the smallest number that has 10 representations as a sum of three positive squares: 594 = 1² + 8² + 23² = 3² + 3² + 24² = 3² + 12² + 21² = 4² + 7² + 23² = 4² + 17² + 17² = 5² + 13² + 20² = 7² + 16² + 17² = 8² + 13² + 19² = 12² + 15² + 15² = 13² + 13² + 16².

594 = 1⁵ + 2⁹ + 3⁴.

594 is the sum of 10 consecutive primes: 594 = 41 + 43 + 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79.

USS Permit (SSN-594) was a nuclear submarine that was launched in 1961 and decommissioned in 1991.

Source: What's Special About This Number?

976

2011-09-30T06:00:00.003-04:00

976 = 2⁴ x 61.

976 is a decagonal number. It is also a centered triangular number.

976 has a square formed by inserting a block of digits inside the original number: 976² = 952,576.

976 has a representation as a sum of two squares: 976 = 20² + 24².

976 is a divisor of 11⁴ - 1.

976-EVIL is a 1989 horror film directed by Robert Englund.

Source: What's Special About This Number?

680

2011-09-29T06:00:00.003-04:00

680 = 2³ x 5 x 17.

680 is the 15th tetrahedral number. It is the smallest tetrahedral number that is also the sum of two tetrahedral numbers: 680 = 560 + 120.

680 has two representations as a sum of two squares: 680 = 2² + 26² = 14² + 22².

680 is 404 in base 13.

680 can be written as the sum of distinct odd powers of two: 680 = 2³ + 2⁵ + 2⁷ + 2⁹.

WCBM AM 680 is a talk radio station in Baltimore.

Source: Number Gossip

458

2011-09-28T06:00:00.002-04:00

458 = 2 x 229.

458 has a representation as a sum of two squares: 458 = 13² + 17².

458 is a number that does not have any digits in common with its cube: 458³ = 96,071,912.

458² contains exactly six different digits: 458² = 209,764.

The Ferrari 458 Italia is a sports car that was introduced in 2009.

Source: What's Special About This Number?

156

2011-09-27T06:00:00.005-04:00

156 = 2² x 3 x 13. It is a pronic number because it is the product of two consecutive numbers: 156 = 12 x 13.

156 is 1111 in base 5.

156 is a dodecagonal number.

156 is the number of graphs with six vertices.

A clock will strike 156 times in the course of a day.

Source: Number Gossip

452

2011-09-26T06:00:00.002-04:00

452 = 2² x 113.

452 has a representation as a sum of two squares: 452 = 14² + 16².

452 is a divisor of 15⁴ - 1.

452 is 381 in base 11 and 318 in base 12. It is 202 in base 15.

452 is the sum of seven nonzero 4th powers.

The Petronas Towers in Kuala Lumpur, Malaysia, are 452 meters tall (including antenna spires).

Source: The Positive Integers

857

2011-09-23T06:00:00.003-04:00

857 is a prime number.

857 has a representation as a sum of two squares: 857 = 4² + 29².

857 and 859 form a twin prime pair.

857 is the hypotenuse of a primitive Pythagorean triple: 857² = 232² + 825².

142,857 x 5 = 714,285 = 857² - 142², where 857,142 = 142,857 x 6.

857 is 1011202 in base 3. It is 272 in base 19.

857 is the sum of three consecutive primes: 857 = 281 + 283 + 293.

Glasenappia 857 is an asteroid discovered in 1916.

Source: Wikipedia

339

2011-09-22T06:00:00.002-04:00

339 = 3 x 113.

339 is the number of ways to divide 5 black and 5 white beads into piles.

339³ = 38,958,219 = (389 - 58 - 2 + 1 + 9)³.

339 is 2324 in base 5 and 1323 in base 6. It is 523 in base 8.

339 is the sum of the squares of three consecutive primes: 339 = 7² + 11² + 13².

The Gibson ES-339 is a custom hand-crafted electric guitar.

Source: What's Special About This Number?

143

2011-09-21T06:00:00.004-04:00

143 = 11 x 13.

143 is the smallest brilliant number whose reversal, 341, is a different brilliant number.

143 is an aspiring number.

The last 143 digits of 143¹⁴³ form a prime number.

143 is the number of three-digit primes.

Every positive integer is the sum of at most 143 seventh powers.

143² is a divisor of 143143.

143 is the sum of three consecutive primes and the sum of seven consecutive primes: 143 = 43 + 47 + 53 = 11 + 13 + 17 + 19 + 23 + 29 + 31.

Vickers Type 143 was a British single-seat biplane designed and built in 1929.

Source: Number Gossip

247

2011-09-20T06:00:00.003-04:00

247 = 13 x 19. Its digits sum to the smallest prime factor: 2 + 4 + 7 = 13.

247 is a pentagonal number.

247 is the smallest possible difference between two integers that together contain each digit exactly once: 247 = 50,123 - 49876.

247² is one of six square numbers that use the same digits: 247² = 61,009; 130² = 16.900; 140² = 19,600; 310² = 96,100; 103² = 10,609; and 301² = 90,601.

247 Eukrate is a large, dark asteroid discovered in 1885.

Source: Prime Curios!

551

2011-09-19T06:00:00.003-04:00

551 = 19 x 29.

551 is the sum of three consecutive primes: 551 = 179 + 181 + 191.

551 is a centered decagonal number.

551 is the number of trees with 12 vertices.

551 is 202102 in base 3 and 20213 in base 4.

551 is a divisor of 30³ - 1.

551 Ortrud is an asteroid discovered in 1904.

Source: What's Special About This Number?

6200

2011-09-16T06:00:00.002-04:00

6200 = 2³ x 5² x 31.

6200 is 22111122 in base 3 and 8448 in base 9. It is 14070 in base 8.

6200 is a harmonic divisor number.

6200 is a multiple of 8 with a digit sum of 8.

6200 is a divisor of 99⁶ - 1.

The GeForce 6200 from Nvidia is a graphics processing unit introduced in 2004.

Source: What's Special About This Number?

621

2011-09-15T06:00:00.002-04:00

621 = 3³ x 23.

621 is the number of ways to 9-color a tetrahedron.

621 is 4441 in base 5. It is 515 in base 11.

621² = 385,641 contains exactly six different digits.

621 is the sum of two distinct positive pentatope numbers: 621 = 126 + 495.

The USS Haddock (SSN-621) was a nuclear-powered submarine launched in 1966 and decommissioned in 1993.

Source: What's Special About This Number?

410

2011-09-14T06:00:00.002-04:00

410 = 2 x 5 x 41.

410 has two representations as a sum of two squares: 410 = 7² + 19² = 11² + 17². 410 is the smallest number that can be represented as the sum of the squares of distinct primes in two different ways.

410 is 120012 in base 3, 12122 in base 4, and 1124 in base 7. It is 505 in base 9 and 343 in base 11.

410 is the sum of six consecutive primes: 410 = 57 + 61 + 67 + 71 + 73 + 79.

410 is the telephone area code for the Baltimore area of the state of Maryland.

Source: Prime Curios!

1099

2011-09-13T06:00:00.002-04:00

1099 = 7 x 157.

1099 is 777 in base 12.

1099 = 1 + 0 + 999 + 99.

1099 and 1099² = 1,207,801 have the same digit sum: 1 + 0 + 9 + 9 = 1 + 2 + 0 + 7 + 8 + 0 + 1 = 19.

1099 is the sum of seven consecutive primes: 1099 = 139 + 149 + 151 + 157 + 163 + 167 + 173.

In the United States the 1099 IRS tax form shows how much an independent contractor made from a certain business.

Source: What's Special About This Number?

222

2011-09-12T06:00:00.002-04:00

222 = 2 x 3 x 37.

222 is the number of integer partitions of 28 into distinct parts.

222 is the smallest number with three prime digits.

The number 222² + 222²² + 222²²² + 1 is a prime.

222 is 1010 in base 6. It is 141 in base 13.

Room 222 was a TV show that aired from 1969 to 1974.

Source: Number Gossip

8184

2011-09-09T06:00:00.002-04:00

8184 = 2³ x 3 x 11 x 31.

8184 is a divisor of 97⁵ - 1.

8184 has the representation 2¹³ - 8.

8184 is 1333320 in base 4 and 12203 in base 9. The set of base 4 digits of 8184 equals the set of base 9 digits: {0, 1, 2, 3}. 8184 contains exactly the same digits (with the correct multiplicity) in three different smaller bases.

The product of the digits of 8184 is 8 x 1 x 8 x 4 = 256 = 4⁴, where 4 is the number of digits.

8184² = 66,977,856 contains no digit less than 5.

Lego set 8184 is an RC Racer.

Source: What's Special About This Number?

807

2011-09-08T06:00:00.002-04:00

807 = 3 x 269.

807!/708! - 1 is a prime number.

807 and 807² = 651,249 combined use different digits.

807 is the sum of two pentagonal numbers in exactly two ways: 807 = 715 + 92 = 477 + 330.

807 is the sum of 13 positive fifth powers.

Telephone area code 807 covers the northwestern portion of the province of Ontario.

Source: Prime Curios!

405

2011-09-07T06:00:00.003-04:00

405 = 3⁴ x 5.

405 has a representation as a sum of two squares: 405 = 9² + 18².

405 is a pentagonal pyramidal number.

405 is 120000 in base 3 and 12111 in base 4. It is 500 in base 9.

405 is a tridecagonal number.

405 is the telephone area code for central Oklahoma.

Source: What's Special About This Number?

502

2011-09-06T06:00:00.002-04:00

502 = 2 x 251.

502 is a divisor of 5²⁵ - 1.

502 is an Eulerian number.

502 and its reversal (205) are both semiprimes (the product of two primes).

502 is a number such that the sum of its base 2 digits (1 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 0 = 7) is equal to the sum of its base 10 digits (5 + 0 + 2 = 7).

Telephone area code 502 serves Louisville, Kentucky, and the surrounding area.

Source: On-Line Encyclopedia of Integer Sequences

1318

2011-09-02T06:00:00.003-04:00

1318 = 2 x 659.

1318 is a semiprime with a prime sum of factors: 2 + 659 = 661, a prime. 1318 is a semiprime that is 1 less than a prime, 1319.

1318 is a divisor of 55⁷ - 1.

1318 is 414 in base 18.

1318 is the rectilinear crossing number of a complete graph of 19 nodes.

IC 1318 is the Gamma Cygni nebula.

Source: On-Line Encyclopedia of Integer Sequences

367

2011-09-01T06:00:00.003-04:00

367 is a prime number.

367 is a prime number whose digits are distinct and, expressed in English, are in reverse alphabetical order.

367 is the sum of two consecutive composite numbers: 367 = 183 + 184.

367 is the largest number whose square has strictly increasing digits: 367² = 134,689.

367 is 11233 in base 4. It is 557 in base 8 and 447 in base 9. It is 267 in base 12, 197 in base 15, and 127 in base 18.

The Pythagorean Proposition, by early 20th-century professor Elisha Scott Loomis, is a collection of 367 proofs of the Pythagorean theorem.

Source: Number Gossip

592

2011-08-31T06:00:00.001-04:00

592 = 2⁴ x 37.

592 has a representation as a sum of two squares: 592 = 4² + 24².

592 is 2424 in base 6. It is 727 in base 9 and 414 in base 12. It is 250 in base 16.

592 is a Moran number: 592 divided by the sum of its digits (5 + 9 + 2) = 16) is a prime number (37).

Permuting the digits of 592 produces a square: 529 = 23².

Camelback 592 is a locomotive in the collection of the Baltimore & Ohio Railroad Museum.

Source: On-Line Encyclopedia of Integer Sequences

1317

2011-08-30T06:00:00.002-04:00

1317 = 3 x 439.

1317 is palindromic in base 2 (binary): 1010001000101. It is 1210210 in base 3.

1317 is the concatenation of the sixth and seventh primes. It is also the concatenation of the seventh Fibonacci number and the seventh prime.

131771317 and 713177 are both primes.

1317 is a semiprime for which the product of its digits is also a semiprime: 1 x 3 x 1 x 7 = 21 = 3 x 7.

NGC 1317 is a galaxy with a starburst ring.

Source: On-Line Encyclopedia of Integer Sequences

3642

2011-08-29T06:00:00.003-04:00

3642 = 2 x 3 x 607.

3642 is 320322 in base 4 and 7072 in base 8.

3642 is the number of labeled topologies with 5 points.

3642 and 3642² use only the digits 1, 2, 3, 4, and 6. The internal digits of the squared number include only the digits of the number.

36423641 and 36423643 are a pair of twin primes.

3642 is one of the 36 Class steam locomotives operated by the New South Wales Government Railways.

Source: On-Line Encyclopedia of Integer Sequences

311

2011-08-26T06:00:00.004-04:00

311 is a prime number.

311 and 313 form a twin prime pair.

311 is the 11th three-digit prime for which the sum of the squares of its digits is also a prime: 3² + 1² + 1² = 11, a prime.

311 is the smallest number expressible as the sum of consecutive primes in four ways: 311 = 101 + 103 + 107 = 53 + 59 + 61 + 67 + 71 = 31 + 37 + 41 + 43 + 47 + 53 + 59 = 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47.

311 is a rock/reggae band.

Source: Prime Curios!