Numbers / 911

The Number 911

911 is prime: only 1 and 911 divide it evenly; the next prime after 911 is 919. 911's proper divisors total just 1, 910 short of 911, the deficient case most of 911's neighbors share too. 911 has a digit sum of 11; for 911, the digital root works out to 2. 911 shares no factor with 2-12; 911's own divisors start beyond that range. 911 is 1110001111 in binary and 38F in hex; as a Roman numeral it's CMXI.