Numbers / 687

The Number 687

687 is composite: factorization 3 × 229. That gives 687 exactly 4 divisors: 1, 3, 229, 687. 687's proper divisors total just 233, 454 short of 687, the deficient case most of 687's neighbors share too. 687 has a digit sum of 21; for 687, the digital root works out to 3. 687: 3 all divide 687 evenly, out of 2-12. 687 is 1010101111 in binary and 2AF in hex; as a Roman numeral it's DCLXXXVII.