Numbers / 731

The Number 731

731 is composite: factorization 17 × 43. That gives 731 exactly 4 divisors: 1, 17, 43, 731. 731's proper divisors total just 61, 670 short of 731, the deficient case most of 731's neighbors share too. 731 has a digit sum of 11; for 731, the digital root works out to 2. 731 shares no factor with 2-12; 731's own divisors start beyond that range. 731 is 1011011011 in binary and 2DB in hex; as a Roman numeral it's DCCXXXI.