1160

1160 = 2 x 2 x 2 x 5 x 29.

1160 is divisible by the sum of its prime factors (40) (A046346).

1160 is an octagonal number (A000567).

1160 is a cake number (A000125). It is the maximum number of pieces into which a cylindrical cake can be cut with 19 straight-plane cuts.

The sum of the squares of the first 1160 primes is prime (A098561).

1160 is the smaller of two consecutive numbers each divisible by a cube (A068140).

1160 is 1120222 in base 3, 102020 in base 4, and 2210 in base 8. It is 3245 in base 7. It is 808 in base 12 and 404 in base 17. It is 488 in base 16.

Source: Number Gossip

3201

3201 = 3 x 11 x 97.

3201 is an octagonal number (A000567).

3201 is the number of regions in a regular 33-gon that are hexagons (A067153).

3201 is the sum of the first 22 Sophie Germain primes (A066819).

3201 divides 98² - 1.

3201 is 12222 in base 7.

Source: OEIS

1825

1825 = 5 x 5 x 73.

1825 is an octagonal number (A000567).

1825 is the smallest number whose square begins with three 3s (A131573 and A025286 and A025304 and A034982).

1825 has three representations as a sum of two squares (A025313): 1825 = 12² + 41² = 15² + 40² = 23² + 36².

1825 is the hypotenuse of two primitive Pythagorean triples: 1825² = 767² + 1656² = 984² + 1537².

1825 divides 74² - 1.

Source: What's Special About This Number?

5461

5461 = 43 x 127.

5461 is 1010101010101 in binary (base 2).

5461 is 1111111 in base 4 (A053716). It divides 4⁷ - 1.

5461 is a centered heptagonal number (A069099). It is also an octagonal (star) number (A000567) and a concentric tridecagonal number (A195045).

5461 is a Poulet number.

Source: What's Special About This Number?

4720

4720 = 2 x 2 x 2 x 2 x 5 x 59.

4720 is a structured truncated cubic number (A100152).

4720 is an octagonal (star) number (A000567). The product of its digits is also an octagonal number (A117083): 4 x 7 x 2 x 0 = 0.

4720 is a number such that 4720 and 4720² = 22278400 use only the digits 0, 2, 4, 7, and 8 (A136906).

Source: What's Special About This Number?

341

341 = 11 x 31.

341 is 101010101 in base 2 (binary). It is 11111 in base 4.

341 is an octagonal number and a centered cube number.

341 is the first composite number to disprove an ancient Chinese conjecture (circa 500 B.C.) that n is a prime number if and only if n divides the number 2ⁿ - 2. The number 2³⁴¹ - 2 is divisible by 341, a composite number. 341 is the smallest pseudoprime in base 2.

341 is the sum of seven consecutive primes: 341 = 37 + 41 + 43 + 47 + 53 + 59 + 61.

341 = 4⁰ + 4¹ + 4² + 4³ + 4⁴.

341 is the smallest number with seven representations as a sum of three positive squares: 341 = 1² + 4² + 18² = 1² + 12² + 14² = 2² + 9² + 16² = 4² + 6² + 17² = 4² + 10² + 15² = 6² + 7² + 16² = 8² + 9² + 14².

Source: Number Gossip

936

936 = 2 x 2 x 2 x 3 x 3 x 13.

936 is an octagonal number (A000567) and a pentagonal pyramidal number (A002411).

936 is 12221 in base 5.

936³ = 820,025,856 = (820 + 02 + 58 + 56)³.

936 has a representation as a sum of two squares: 936 = 6² + 30².

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

Source: What's Special About This Number?

280

280 = 2 x 2 x 2 x 5 x 7.

280 is 100011000 in base 2 (binary).

280 has a unique representation as a sum of three squares: 280 = 6² + 10² + 12².

The sum of the first 280 consecutive primes mod 280 is prime.

280 is the number of ways 18 people around a round table can shake hands in a non-crossing way, up to rotation.

280 is an octagonal number.

Source: Prime Curios!

408

408 = 2 x 2 x 2 x 3 x 17.

408 is the sum of four consecutive primes: 408 = 97 + 101 + 103 + 107. It is also the sum of eight consecutive primes: 408 = 37 + 41 + 43 + 47 + 53 + 59 + 61 + 67.

408 is an octagonal number.

408 is the eighth Pell number.

408 is 3113 in base 5, 1122 in base 7, and 212 in base 14.

408 is the telephone area code for the Silicon Valley, California.

Source: What's Special About This Number?

225

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

2133

2133 = 3³ x 79.

2133 is a 2-hyperperfect number.

2133 is an octagonal number.

2133 is a lucky number that is divisible by the sum of its digits (9).

The HP 2133 Mini-Note is a small laptop computer.

Source: What's Special About This Number?

560

560 = 2⁴ x 5 x 7.

560 has a unique representation as a sum of three squares: 560 = 4² + 12² + 20².

560 is the 14th tetrahedral number. 560 is also an octagonal number.

560 is 202202 in base 3 and 2332 in base 6.

560 is the number of different moves a bishop can make on a chessboard.

Source: Number Gossip

736

736 = 2⁵ x 23.

736 has a unique representation as a sum of three squares: 736 = 4² + 12² + 24².

736 has the representation 3⁶ + 7.

736 is an octagonal number. It is also a centered heptagonal number.

736 is the smallest number such that n and 2ⁿ end with the same three digits.

The Revox G36 (or 736 in Great Britain) was a mono/stereo reel-to-reel recording machine.

Source: Number Gossip

481

481 = 13 x 37.

481 has two representations as a sum of two squares: 481 = 9² + 20² = 15² + 16².

481 is the hypotenuse of two primitive Pythagorean triples: 481² = 31² + 480² = 319² + 360².

481 is an octagonal number.

The Great Pyramid of Giza in Egypt is 481 feet high.

Source: WolframAlpha