Numbers / 651

The Number 651

651 is composite: factorization 3 × 7 × 31. That gives 651 exactly 8 divisors: 1, 3, 7, 21, 31, 93, 217, 651. 651's proper divisors total just 373, 278 short of 651, the deficient case most of 651's neighbors share too. 651 has a digit sum of 12; for 651, the digital root works out to 3. 651: 3, 7 all divide 651 evenly, out of 2-12. 651 is 1010001011 in binary and 28B in hex; as a Roman numeral it's DCLI.