Numbers / 819

The Number 819

819 is composite: factorization 3^2 × 7 × 13. That gives 819 exactly 12 divisors: 1, 3, 7, 9, 13, 21, 39, 63, 91, 117, 273, 819. 819's proper divisors total just 637, 182 short of 819, the deficient case most of 819's neighbors share too. 819 has a digit sum of 18; for 819, the digital root works out to 9. 819: 3, 7, 9 all divide 819 evenly, out of 2-12. 819 is 1100110011 in binary and 333 in hex; as a Roman numeral it's DCCCXIX.