Numbers / 557

The Number 557

557 is prime: only 1 and 557 divide it evenly; the next prime after 557 is 563. 557's proper divisors total just 1, 556 short of 557, the deficient case most of 557's neighbors share too. 557 has a digit sum of 17; for 557, the digital root works out to 8. 557 shares no factor with 2-12; 557's own divisors start beyond that range. 557 is 1000101101 in binary and 22D in hex; as a Roman numeral it's DLVII.