Numbers / 63

The Number 63

63 is composite: factorization 3^2 × 7. That gives 63 exactly 6 divisors: 1, 3, 7, 9, 21, 63. 63's proper divisors total just 41, 22 short of 63, the deficient case most of 63's neighbors share too. 63 has a digit sum of 9; for 63, the digital root works out to 9. 63: 3, 7, 9 all divide 63 evenly, out of 2-12. 63 is 111111 in binary and 3F in hex; as a Roman numeral it's LXIII.