Numbers / 921

The Number 921

921 is composite: factorization 3 × 307. That gives 921 exactly 4 divisors: 1, 3, 307, 921. 921's proper divisors total just 311, 610 short of 921, the deficient case most of 921's neighbors share too. 921 has a digit sum of 12; for 921, the digital root works out to 3. 921: 3 all divide 921 evenly, out of 2-12. 921 is 1110011001 in binary and 399 in hex; as a Roman numeral it's CMXXI.