Numbers / 649

The Number 649

649 is composite: factorization 11 × 59. That gives 649 exactly 4 divisors: 1, 11, 59, 649. 649's proper divisors total just 71, 578 short of 649, the deficient case most of 649's neighbors share too. 649 has a digit sum of 19; for 649, the digital root works out to 1. 649: 11 all divide 649 evenly, out of 2-12. 649 is 1010001001 in binary and 289 in hex; as a Roman numeral it's DCXLIX.