Numbers / 631

The Number 631

631 is prime: only 1 and 631 divide it evenly; the next prime after 631 is 641. 631's proper divisors total just 1, 630 short of 631, the deficient case most of 631's neighbors share too. 631 has a digit sum of 10; for 631, the digital root works out to 1. 631 shares no factor with 2-12; 631's own divisors start beyond that range. 631 is 1001110111 in binary and 277 in hex; as a Roman numeral it's DCXXXI.