5557 is a prime number.
5557 is palindromic in base 2: 1010110110101.
5557 has a representation as the sum of two squares: 5557 = 92 + 742.
5557 is the hypotenuse of a primitive Pythagorean triple: 55572 = 13322 + 53952.
In summing primes, 2 + 3 + 5 + 7 + 11 + . . . + 3833 = 3847 + 3851 + . . . + 5557.
NGC 5557 is a galaxy in the constellation Bootes.
Source: Prime Curios!