Numbers / 251

The Number 251

251 is prime: only 1 and 251 divide it evenly; the next prime after 251 is 257. 251's proper divisors total just 1, 250 short of 251, the deficient case most of 251's neighbors share too. 251 has a digit sum of 8; for 251, the digital root works out to 8. 251 shares no factor with 2-12; 251's own divisors start beyond that range. 251 is 11111011 in binary and FB in hex; as a Roman numeral it's CCLI.