Numbers / 315

The Number 315

315 is composite: factorization 3^2 × 5 × 7. That gives 315 exactly 12 divisors: 1, 3, 5, 7, 9, 15, 21, 35, 45, 63, 105, 315. 315's proper divisors total just 309, 6 short of 315, the deficient case most of 315's neighbors share too. 315 has a digit sum of 9; for 315, the digital root works out to 9. 315: 3, 5, 7, 9 all divide 315 evenly, out of 2-12. 315 is 100111011 in binary and 13B in hex; as a Roman numeral it's CCCXV.