Wednesday, December 12, 2012

395

395 = 5 x 79.

395 is the sum of three consecutive primes (A034961): 395 = 127 + 131 + 137. It is also the sum of five consecutive primes (A034964): 395 = 71 + 73 + 79 + 83 + 89.

395 is the smallest multiple of 5 with a digit sum of 17 (A069534).

395 is the smallest sum of 5 consecutive odd primes that is a multiple of 5 (A132810).

395 is the sum of 15 but no fewer nonzero fourth powers (A046046).


Source: On-Line Encyclopedia of Integer Sequences

Tuesday, December 11, 2012

533

533 = 13 x 41.

533 is the number of degree sequences for graphs with five vertices.

533 has two representations as a sum of two squares: 533 = 22 + 232 = 72 + 222.

533 is the hypotenuse of two primitive Pythagorean triples: 5332 = 922 + 5252 = 3082 + 4352.

533 is 201202 in base 4. It is 191 in base 19.

533 is the sum of three consecutive primes: 533 = 173 + 179 + 181. It is also the sum of five consecutive primes: 533 = 101 + 103 + 107 + 109 + 113.



Source: What's Special About This Number?

Monday, December 10, 2012

885

885 = 3 x 5 x 59.

885 is a divisor of 584 - 1.

885!/588! - 1 is prime.

885 is an enneagonal pyramidal number (A007584).

885 is 31311 in base 4 and 311 in base 17. It is 531 in base 13.


Source: Prime Curios!

Friday, December 7, 2012

595

595 = 5 x 7 x 17.

595 is the 34th triangular number (the sum of the first 34 integers).

595 is a centered nonagonal number.

595 is the number of ways to tile a 3 x 18 rectangle with 3 x 1 rectangles.

595 is 151 in base 22.


Source: Whar's Special About This Number?

Thursday, December 6, 2012

996

996 = 2 x 2 x 3 x 83.

996 has a square (992016) formed by inserting a block of digits inside itself (A045953, A046829), A046851, and A086457).

The sum of the squares of the first 996 primes is a prime (A098561).

996 is the number of cubic lattice walks that start and end at the origin after 6 steps, not touching the origin at intermediate stages (A049037).


Source: What's Special About This Number?

Wednesday, December 5, 2012

436

436 = 2 x 2 x 109.

436 has a representation as a sum of two squares: 436 = 62 + 202.

436 is the maximum number of regions into which 29 lines divide a plane (A000124).

436 is the smallest number whose cube (82881856) contains four 8s.

436 is 232 in base 14.

436 is the number of ways to cover (without overlapping) a ring lattice (necklace) of 29 sites with molecules that are 8 sites wide (A058365).


Source: What's Special About This Number?

Tuesday, December 4, 2012

586

586 = 2 x 293.

586 is the smallest number that appears in its factorial six times.

586 is 4321 in base 5.

586 is the sum of three distinct positive cubes (A024975): 586 = 73 + 63 + 33.

586 has a representation as a sum of two squares: 586 = 152 + 192.

586 is a truncated octahedral number.


Source: What's Special About This Number?

Monday, December 3, 2012

684

684 = 2 x 2 x 3 x 3 x 19.

684 has the representation 684 = 36 - 45.

684 is the sum of three consecutive cubes (A024975): 684 = 53 + 63 + 73.

684 is 221100 in base 3.

684 is the largest number that is 38 times the sum of its digits (A052489): 684 = 38 x 18.


Halley's Comet was visible from Earth in the year 684.

Source: What's Special About This Number?

Friday, November 30, 2012

499

499 is a prime number.

499 is the smallest prime that is the sum of a prime number of first odd primes: 499 = 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53 + 59 + 61.

499499 ends with the digits 499499. In general, its odd powers end with 499 and its even powers end with 001.

Separate 499 into two (49, 9) and three (4, 9, 9) groups and get two primes after replacing each subset with each subset with its square root, namely 73 and 233. Replacing each digit of these latter two primes with their cubes results in two new primes: 34327 and 82727.

499 is the number of ways to place 26 points on a 13 x 13 grid so that no three points are on a line.

499 is the smallest number with the property that its first 12 multiples contain the digit 9.


499 seconds is the average time interval for sunlight from the sun to reach Earth.

Source: Prime Curios!

Thursday, November 29, 2012

1507

1507 = 11 x 137.

1507 is a divisor of 1004 - 1 (A027890). It is also a divisor of 1016 - 1 (A111211).

1507 is the number of partitions of 32 that do not contain 1 as a part (A002865).

1507 is the sum of exactly three sets of Fibonacci numbers (A122195).

The sums of the digits of 1507 in base 2 (10111100011), base 3 (2001211), and base 5 (22012) are equal (A135121).


The word "America" was first used on a map published in the year 1507.

Source: What's Special About This Number?

Wednesday, November 28, 2012

1422

1422 = 2 x 3 x 3 x 79.

1422 is the number of ways to stack 27 boxes in a line so that each box lies on the table or on a box next to two boxes (A001522).

1422 is a divisor of 553 - 1.

14222 = 2022084 has only even digits (A030097).

The sum of the digits of 1422 and 14222 are both squares (A197125): 1 + 4 + 2 + 2 = 9 = 32 and 2 + 0 + 2 + 0 + 8 + 4 = 16 = 42.


Source: What's Special About This Number?

Tuesday, November 27, 2012

394

394 = 2 x 197.

394 has a representation as a sum of two squares: 394 = 132 + 152.

394 is a Schroeder number (A006318).

394 is 202 in base 14.

The sum of the digits of 394 equals the sum of the digits of the 394th prime (2707) (A033549).

394 is the middle semiprime of three consecutive semiprimes: 393, 394, 395.


Source: What's Special About This Number?

Monday, November 26, 2012

487

487 is a prime number.

487 is the smallest prime p such that p and p3 (115501303) have the same digit sum: 4 + 8 + 7 = 19 = 1 + 1 + 5 + 5 + 0 + 1 + 3 + 0 + 3.

487 is the number of Hadamard matrices of order 28.

487 is 200001 in base 3. It is 13213 in base 4 and 2131 in base 6. It is 747 in base 8 and 191 in base 18.

487 is the sum of three consecutive primes: 487 = 157 + 163 + 167.



Source: Number Gossip

Wednesday, November 21, 2012

371

371 = 7 x 53.

371 is a narcissistic number (Armstrong number): 371 = 33 + 73 + 13.

371 is the largest known semiprime that is also the sum of consecutive prime numbers from 7 (smallest prime factor) to 53 (largest prime factor): 371 = 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53.

371 is the sum of three consecutive primes and seven consecutive primes: 371 = 113 + 117 + 131 = 41 + 43 + 47 + 53 + 59 + 61 + 67.

371 is the sum of five positive fifth powers: 371 = 35 + 25 + 25 + 25 + 25.


Source: Number Gossip

Tuesday, November 20, 2012

561

561 = 3 x 11 x 17.

561 is 1000110001 in base 2 (binary) (A006995).

561 is the 33rd triangular number (A000217), the sum of the first 33 integers. It is also a hexagonal number (A000384) and a dodecagonal number (A051624).

561 is the smallest Carmichael number (A002997).

561 is a centered icosahedral number (cuboctahedral number) (A005902).


Source: Number Gossip

Monday, November 19, 2012

952

952 = 2 x 2 x 2 x 7 x 17.

952 = 93 + 53 + 23 + (9 x 5 x 2).

952 is 4224 in base 6.

952 is the number of regions in an 14-gon with all diagonals drawn (A007678).

952 is a number that can be expressed as the difference of squares of primes in just one distinct way (A090781).

952 is the number of possible queen moves on a 7 x 7 chessboard (A035005).


952 Caia is an asteroid orbiting the sun.

Source: What's Special About This Number?

Friday, November 16, 2012

454

454 = 2 x 227.

454 is the largest number known that cannot be written as a sum of seven or fewer cubes (A018889).

454 is a Smith number (A006753). The sum of its digits (4 + 5 + 4 = 13) is equal to the sum of the digits of its prime factors (2 + 2 + 2 + 7 = 13).

1 + 8 + 10 + 17 = 36 = 2 + 5 + 13 + 16
12 + 82 + 102 + 172 = 454 = 22 + 52 + 132 + 162
13 + 83 + 103 + 173 = 6426 = 23 + 53 + 133 + 163

454 is 383 in base 11 (A029966) and 246 in base 14.


Source: What's Special About This Number?

Thursday, November 15, 2012

2034

2034 = 2 x 3 x 3 x 113.

2034 is the number of self-avoiding walks of length 9.

2034 is the number of ways of writing 4 as a sum of nine squares (A008452).

2034 has a representation as a sum of two squares: 2034 = 32 + 452.

2034 is a divisor of 3516 - 1.

2034 is 909 in base 15. It is 369 in base 25.


Source: What's Special About This Number?

Wednesday, November 14, 2012

2006

2006 = 2 x 17 x 59.

2006 is 2202022 in base 3. It is 434 in base 22.

2006 is a term in the sequence starting with 1, then adding 35, then repeatedly reversing the digits and adding 35 (A118632).

2006 is a multiple of 17 such that its reversal minus 1 (6001) is also a multiple of 17 (A166398).

2006 is the number of line segments connecting exactly 10 points in a 26 x 26 grid (A177726).


A transit of Mercury as seen from Earth took place in the year 2006 (A171466).

Source: On-Line Encyclopedia of Integer Sequences

Tuesday, November 13, 2012

1203

1203 = 3 x 401.

1203 is a divisor of 204 - 1.

1203 is the smallest number n for which the concatenation n, (n + 1), (n + 2), . . . . (n + 34) is prime (A052079).

1203 is 102303 in base 4, 14303 in base 5, and 303 in base 20. It is 717 in base 13.

12032 = 1447209 and 12033 = 1740992427 have the same set of digits (A029797 and A045620).


Source: What's Special About This Number?

Monday, November 12, 2012

1010

1010 = 2 x 5 x 101.

1010 has two representations as a sum of two squares: 1010 = 72 + 312 = 132 + 292.

1010 is the sum of two distinct powers of 10 (A052216 and A038444): 1010 = 103 + 101.

1010 is the number of ways to tile a 5 x 12 rectangle with pentominoes.

1010 is 2642 in base 7 and 1342 in base 9. It is 262 in base 21.

1010 is the number of primes less than 104 that do not contain the digit 0 (A091634).


Source: What's Special About This Number?

Friday, November 9, 2012

902

902 = 2 x 11 x41. It is the smallest number beginning with 9 that is the product of exactly three primes (A106419).

902 is a value of n such that n(n + 7) is palindromic: 902(909) = 819918.

902 is 1020102 in base 3, 12102 in base 5, and 4102 in base 6. It is 1212 in base 9 and 321 in base 17. It is 545 in base 13 and 252 in base 20.

902, 903, and 904 have the same number of divisors (A005238).

902 is a multiple of 11 such that sum of its digits is also a multiple of 11 (A216995).


Source: What's Special About This Number?

Thursday, November 8, 2012

1483

1483 is a prime number.

1481 and 1483 form a twin prime pair.

1483 is the smallest prime that is the sum of three prime cubes: 1483 = 33 + 53 + 113.

1483 has the representation 2 x 36 + 25.

1483 is a divisor of 383 - 1.


The Petronas Towers in Kuala Lumpur, Malaysia, are 1483 feet tall.

Source: Prime Curios!

Wednesday, November 7, 2012

4656

4656 = 2 x 2 x 2 x 2 x 3 x 97.

4656 is the 96th triangular number, with digit sum 21 (A068131).

4656 is 1020300 in base 4 and 1230 in base 16.

4656 is a structured pentagonal hexacontahedral number (A100169).

4656 is the number of 3 x 3 arrays of squares on integers summing to 18 (A159401).


Source: Numeropedia

Tuesday, November 6, 2012

442

442 = 2 x 13 x 17.

442 has two representations as a sum of two squares: 442 = 12 + 212 = 92 + 192.

442 is the smallest composite number n that divides F(n - 1) where F(k) are the Fibonacci numbers.

442 is the number of planar partitions of 13.

442 is the sum of eight consecutive primes: 442 = 41 + 43 + 47 + 53 + 59 + 61 + 67 + 71.

442 is 3232 in base 5 and 101 in base 21.


Source: Number Gossip

Monday, November 5, 2012

693

693 = 3 x 3 x 7 x 11.

693 is 1010110101 in base 2 (binary). It is 3113 in base 6, 414 in base 13, and 313 in base 15.

693 has the representation 693 = 36 - 36.

A primitive Pythagorean triangles of sides (693, 1924, 2045) has area 666,666.


693 is the number of sections in Ludwig Wittgenstein's Philosophical Investigations.

Source: Numeropedia

Friday, November 2, 2012

884

884 = 2 x 2 x 13 x 17.

884 has two representations as a sum of two squares: 884 = 102 + 282 = 202 + 222.

The fifth root of 884 has a decimal part that begins with the digits 884.

884 is 202 in base 21.

The sum of the divisors of 884 is a square (A006532): 1 + 2 + 4 + 13 + 17 + 26 + 34 + 52 + 68 + 221 + 442 + 884 = 1764 = 422.


Source: What's Special About This Number?

Thursday, November 1, 2012

407

407 = 11 x 37.

407 is a divisor of 1003 - 1.

407 is the maximum number of regions into which 28 lines divide the plane.

407 is the largest number that is the sum of the cubes of its digits: 407 = 43 + 03 + 73. It is a narcissistic number.

407 = (7 - 3)3 + 73.

407 is 1515 in base 6.

407 is the sum of three consecutive primes: 407 = 131 + 137 + 139.


Source: Number Gossip

Wednesday, October 31, 2012

182

182 = 2 x 7 x 13.

182 is a pronic number; it is the product of two consecutive numbers: 182 = 13 x 14.

182 is 222 in base 9 and 77 in base 25. It is 20202 in base 3 and 1212 in base 5.

182 is the number of connected bipartite graphs with 8 vertices.

182 = 33 + 33 + 43 + 43 = 142 - 14.


The USS Salmon  (SS-182) was a United States Navy submarine during World War II.

Source: Number Gossip

Tuesday, October 30, 2012

777

777 = 3 x 7 x 37.

777 is a divisor of 1003 - 1.

777 is 3333 in base 6.

Surrounding the number 777 with the number 11 forms the prime numbers 11777, 77711, 1177711, and 11117771111.


The Boeing 777 is a long-range, wide-body, twin-engine jet airliner.

Source: Numeropedia

Monday, October 29, 2012

869

869 = 11 x 79.

869 is the number of different resistances that can be created in a circuit of nine equal resistors (A048211).

The sum of the digits of 869 equals the sum of the digits of the 869th prime (6737) (A033549). 869 and the 869th prime (6737) have only the digit 6 in common (A107937).

869 is a number that yields a prime when 0 is inserted anywhere in it (but not added to the end or beginning) (A216169).


Source: What's Special About This Number?

Friday, October 26, 2012

2142

2142 = 2 x 3 x 3 x 7 x 17.

2142 is a divisor of 554 - 1.

2142 is 32032 in base 5.

2142 is the sum of the totient function for the first 83 integers.

2142 is the number of ways of writing the number 63 as the sum of nine nonnegative cubes (A173682).

2142 is the sum of 10 consecutive primes (A127337): 2142 = 191 + 193 + 197 + 199 + 211 + 223 + 227 + 229 + 233 + 239.


Source: On-Line Encyclopedia of Integer Sequences

Thursday, October 25, 2012

198

198 = 2 x 3 x 3 x 11.

198 is the smallest number with ten representations as a sum of four positive squares: 198 = 12 + 22 + 72 + 122 = 12 + 42 + 92 + 102 = 22 + 32 + 42 + 132 = 22 + 32 + 82 + 112 = 22 + 52 + 52 + 122 = 22 + 72 + 82 + 92 = 32 + 32 + 62 + 122 = 32 + 52 + 82 + 102 = 42 + 52 + 62 + 112 = 62 + 72 + 72 + 82.

198 is the first number between a twin prime pair such that if multiplied by its reversal (198 x 891 = 176418), the product is also between a twin prime pair.

198 can be formed by concatenating 19 and 8, where 19 is the 8th prime number. 198 is the (19 x 8 = 152)nd composite number.

198 = 11 + 99 + 88 = (100 - 1)(100-98).

198 x 27 = 5346 = 18 x 297. Each equality uses each of the nine digits 1 to 9 once.


Source: Prime Curios!

Wednesday, October 24, 2012

756

756 = 2 x 2 x 3 x 3 x 3 x 7.

756 is a pronic number, the product of two consecutive numbers, 27 and 28.

12 x 63 = 756 = 21 x 36.

756 is the maximum number of regions into which 14 spheres divide space.

756!/657! - 1 is a prime.

756 is 11011 in base 5. It is 3300 in base 6.

756 is the sum of six consecutive primes: 756 = 109 + 113 + 127 + 131 + 137 + 139.


Source: Number Gossip

Tuesday, October 23, 2012

387

387 = 3 x 3 x 43.

387 is the lesser of two consecutive numbers divisible by a square (A068781).

387 is 110000011 in base 2 (binary) (A006995).

387 x 7 - 38 = 2671, the 387th prime.

387 is the smallest number with sort-then-add persistence 10.


Source: Prime Curios!

Monday, October 22, 2012

667

667 = 23 x 29. It is the product of two successive primes (A006094) and two distinct Sophie Germain primes (A157344).

667 is the maximum number of regions into which 36 lines divide the plane (A000124).

667 is the number of asymmetric trees with 16 vertices (A000220).

667, 669, and 671 are all semiprimes (A092125).



667 YCF was on the license plates of the car driven by Meeno Paloma (Lou Diamond Philips) in the 2009 movie The Triangle.

Source: Prime Curios!

Friday, October 19, 2012

355

355 = 5 x 71.

355 divided by the prime number 113 yields a nice approximation of pi: 355/113 = 3.141592. . .

355 is the number of labeled topologies with four elements.

355 = 3 x 5! - 5.

355 is 543 in base 8 and 434 in base 9.


Source: Prime Curios!

Thursday, October 18, 2012

740

740 = 2 x 2 x 5 x 37.

740 has two representations as a sum of two squares: 740 = 82 + 262 = 162 + 222.

740 is the number of self-avoiding walks of length 8.

740 is 3232 in base 8 and 345 in base 15.

740 is a hypotenuse for which there exist four distinct integer triangles (A084648).


Source: What's Special About This Number?

Wednesday, October 17, 2012

129

129 = 3 x 43.

129 is 10000001 in base (binary). It is 333 in base 6.

129 is the smallest number with four representations as a sum of three positive squares: 129 = 12 + 82 + 82 = 22 + 22 + 112 = 22 + 52 + 102 = 42 + 72 + 82.

129 is the sum of the first ten primes: 129 = 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29.

129 is the smallest sum of distinct seventh powers: 129 = 17 + 27.


Source: Number Gossip

Tuesday, October 16, 2012

930

930 = 2 x 3 x 5 x 31. It is a pronic number, the product of two consecutive integers (A002378): 930 = 30 x 31. It is also the product of a prime and the previous number (A036689).

930 is the number of even permutations of seven elements with no fixed points.

930 is 656 in base 12 and 567 in base 13.

The sum of the divisors of 930 is a square (A006532): 1 + 2 + 3 + 5 + 6 + 10 + 15 + 30 + 31 + 62 + 93 + 155 + 186 + 310 + 465 + 930 = 2304 = 482.


Source: What's Special About This Number?

Monday, October 15, 2012

1124

1124 = 2 x 2 x 281.

1124 has a representation as a sum of two squares: 1124 = 102 + 322.

1124 is the maximum number of regions into which 34 circles divide a plane.

1124 is a number whose product of digits is equal to its sum of digits: 1 + 1 + 2 + 4 = 8 = 1 x 1 x 2 x 4.

1124 is 686 in base 13, 464 in base 16, 323 in base 19, and 272 in base 22.

1124 is a Leyland number (A076980).


Source: On-Line Encyclopedia of Integer Sequences

Friday, October 12, 2012

617

617 is a prime number.

617 and 619 form a twin prime pair.

617 = 1!2 + 2!2 + 3!2 + 4!2.

617 is the largest multi-digit prime that is exactly half of a number formed with distinct consecutive digits: 1234.

617 has a representation as a sum of two squares: 617 = 162 + 192.

617 is the hypotenuse of a primitive Pythagorean triple: 6172 = 1052 + 6082.

617 is a divisor of 3111 - 1.


Source: Prime Curios!

Thursday, October 11, 2012

914

914 = 2 x 457.

914 has a representation as a sum of two squares: 914 = 172 + 252.

914 is the number of binary rooted trees with 15 vertices.

914 is 494 in base 14.

The sum of the digits of 914 (9 + 1 + 4 = 14) is a substring of 914 (A052018).

Each of the digits of 914 are squares (A046030).


Source: What's Special About This Number?

Wednesday, October 10, 2012

813

813 = 3 x 271.

813 are the first three digits of 813e.

813 is 393 in base 15.

813 is a divisor of 99999 (A027893) and 9999999999 (A027895): 99999/813 = 123 and 9999999999/813 = 12300123.

813 is the concatenation of the sixth Fibonacci number and the sixth prime (A138821).


Source: What's Special About This Number?

Tuesday, October 9, 2012

7011

7011 = 3 x 3 x 19 x 41.

7011 yields a prime whenever 1 is inserted anywhere in the number (A068679 and A216165): 17011, 71011, and 70111 are all primes.

7011 is the sum of three cubes of distinct primes (A138853 and A138854): 7011 = 193 + 53 + 33.

7011 is the number of 16-crossing knots with symmetry group Z2 (A052412).

7011 is the number of 5 x 5 arrays of squares of integers, symmetric about the main diagonal, with all rows summing to 36 (A156385).


Source: On-Line Encyclopedia of Integer Sequences

Friday, October 5, 2012

793

793 = 13 x 61.

793 is one less than twice its reversal: 793 = 2(397) - 1.

793 is a dodecagonal number and a centered dodecagonal number (A003154).

793 has two representations as a sum of two squares: 793 = 32 + 282 = 82 + 272.

793 is the hypotenuse of two primitive Pythagorean triples: 7932 = 1682 + 7752 = 4322 + 6652.


Source: What's Special About This Number?

Thursday, October 4, 2012

598

598 = 2 x 13 x 23.

598 is the largest number that is the sum of its first digit, the square of its second digit, and the cube of its third digit: 598 = 51 + 92 + 83.

598 is 21112 in base 4. It is 4343 in base 5.

598 is a divisor of 474 - 1.

598 is the maximum number of regions into which 13 spheres divide space.


Source: Number Gossip

Wednesday, October 3, 2012

787

787 is a prime number.

The six integers following 787 are divisible by the first six primes, respectively.

787 is the smallest prime that can be represented as the sum of a prime and its reversal in two different ways.

787 is 30103 in base 4, 656 in base 11, and 313 in base 16.

787 is the sum of five consecutive primes: 787 = 149 + 151 + 157 + 163 + 167.


The Boeing 787 Dreamliner is a long-range, mid-size, twin-engine jet airliner.

Source: Prime Curios!

Tuesday, October 2, 2012

254

254 = 2 x 127.

254 is the maximum number of regions into which 22 lines divide a plane. It is a central polygonal number (A000124).

254 is the smallest multi-digit composite number all of whose proper divisors include the digit 2.

254 is the sum of the first 13 semiprimes (A062198).


The state of Texas has 254 counties, the most of any state of the United States.

Source: What's Special About This Number?

Monday, October 1, 2012

403

403 = 13 x 31. It is the smallest semiprime whose factors form a pair of emirps (13 and 31).

403 is 110010011 in base 2.

403 has a unique representation as a sum of three squares: 403 = 32 + 132 + 152.

403 is a heptagonal number.

403 = 23 + 33 + 33 + 53 + 63.


Source: Prime Curios!