Numbers / 811

The Number 811

811 is prime: only 1 and 811 divide it evenly; the next prime after 811 is 821. 811's proper divisors total just 1, 810 short of 811, the deficient case most of 811's neighbors share too. 811 has a digit sum of 10; for 811, the digital root works out to 1. 811 shares no factor with 2-12; 811's own divisors start beyond that range. 811 is 1100101011 in binary and 32B in hex; as a Roman numeral it's DCCCXI.