Numbers / 729

The Number 729

729 is composite: factorization 3^6. That gives 729 exactly 7 divisors: 1, 3, 9, 27, 81, 243, 729. 729's proper divisors total just 364, 365 short of 729, the deficient case most of 729's neighbors share too. 729 also carries: a perfect square, since 27² = 729; and a perfect cube, since 9³ = 729. 729 has a digit sum of 18; for 729, the digital root works out to 9. 729: 3, 9 all divide 729 evenly, out of 2-12. 729 is 1011011001 in binary and 2D9 in hex; as a Roman numeral it's DCCXXIX.