Numbers / 257

The Number 257

257 is prime: only 1 and 257 divide it evenly; the next prime after 257 is 263. 257's proper divisors total just 1, 256 short of 257, the deficient case most of 257's neighbors share too. 257 has a digit sum of 14; for 257, the digital root works out to 5. 257 shares no factor with 2-12; 257's own divisors start beyond that range. 257 is 100000001 in binary and 101 in hex; as a Roman numeral it's CCLVII.