557

557 is a prime number.

557 is a Chen prime. A prime number p is called a Chen prime if p + 2 is either a prime or a product of two primes: (557 + 2 = 559 = 13 x 43). Chen primes are named after Jing Run Chen, who proved in 1966 that there are infinitely many such primes.

557 has a representation as a sum of two squares: 557 = 14² + 19².

557 is the hypotenuse of a primitive Pythagorean triple: 557² = 165² + 532².

USS Johnston (DD-557) was a World War II destroyer in the service of the U.S. Navy.

Source: Wikipedia