655

655 = 5 x 131.

655 is a semiprime (product of two prime numbers) that is the product of two Sophie Germain primes, 5 and 131.

655 is a number that cannot be written as a sum of three squares.

655 is a divisor of 61⁵ - 1.

655 is 22033 in base 4 and 10110 in base 5.

Iran Air Flight 655 was an airliner shot down by U.S. missiles in 1988 toward the end of the Iran-Iraq war.

Source: On-Line Encyclopedia of Integer Sequences

223

223 is a prime number.

223 is a number that cannot be written as a sum of three squares.

223 is the smallest prime with three prime digits. The sum of the digits of first primes up to 223 is 449.

223 is the smallest prime whose reversal has more than two prime divisors: 322 = 2 x 7 x 23.

223 is the final chapter of Mark Haddon's novel The Curious Incident of the Dog in the Night-Time, which uses just prime numbers for its chapters.

Source: Number Gossip

642

642 = 2 x 3 x 107.

642 is a sphenic number because it the product of three distinct primes.

642 is the smallest number with the property that its first six multiples contain the digit 2: 642, 1284, 1926, 2568, 3210, 3852.

642 is 22002 in base 4, 1202 in base 8, and 456 in base 12.

642 Clara is an asteroid orbiting the Sun.

Source: What's Special About This Number?

426

426 = 2 x 3 x 71.

As the product of three distinct primes, 426 is known as a sphenic number.

426 is a stella octangula number. The stella octangula is a stellation of the octahedron.

426 is a number such that 10⁴²⁶ + 3 is a prime.

426 is a multiple of 6 that contains 6 in its decimal representation.

In the 1979 movie Alien, the spaceship Nostromo goes to the desolate planetoid LV-426.

Source: What's Special About This Number?

808

808 = 2³ x 101.

808 has a representation as a sum of two squares: 808 = 18² + 22².

The first 808 digits of 808! form a prime number.

808 is a strobogrammatic number. It is the same number when rotated 180 degrees on an axis perpendicular to the plane on which the number is written.

The 808th Fibonacci number plus and minus 808 results in (13²)-digit primes.

The Roland TR-808 was one of the first programmable drum machines, introduced in early 1980.

Source: Prime Curios!

314

314 = 2 x 157.

314 has a representation as a sum of two squares: 314 = 5² + 17².

314 is the smallest number that can be written as the sum of three positive squares in six ways: 314 = 17² + 4² + 3² = 16² + 7² + 3² = 15² + 8² + 5² = 13² + 9² + 8² = 13² + 12² + 1² = 13² + 9² + 8².

314 is 222 in base 12.

314 is the only number that together with its sixth power, 958468597212736, has each digit from 1 to 9 occurring exactly twice.

314 is the telephone area code for St. Louis, Missouri.

Source: Number Gossip

2265

2265 = 3 x 5 x 151. It has exactly three distinct palindromic prime factors.

The sum of the digits of 2265 equals the sum of the digits of its prime factors: 2 + 2 + 6 + 5 = 3 + 5 + 1 + 5 + 1 = 15.

The product of the digits of 2265 is eight times the sum of the digits: 2 x 2 x 6 x 5 = 8(2 + 2 + 6 + 5) = 120.

2265 is 14253 in base 6. It uses each positive digit just once.

2265 is a year in which January 1 falls on a Sunday.

Source: On-Line Encyclopedia of Integer Sequences.