Numbers / 211

The Number 211

211 is prime: only 1 and 211 divide it evenly; the next prime after 211 is 223. 211's proper divisors total just 1, 210 short of 211, the deficient case most of 211's neighbors share too. 211 has a digit sum of 4; for 211, the digital root works out to 4. 211 shares no factor with 2-12; 211's own divisors start beyond that range. 211 is 11010011 in binary and D3 in hex; as a Roman numeral it's CCXI.