Numbers / 981

The Number 981

981 is composite: factorization 3^2 × 109. That gives 981 exactly 6 divisors: 1, 3, 9, 109, 327, 981. 981's proper divisors total just 449, 532 short of 981, the deficient case most of 981's neighbors share too. 981 has a digit sum of 18; for 981, the digital root works out to 9. 981: 3, 9 all divide 981 evenly, out of 2-12. 981 is 1111010101 in binary and 3D5 in hex; as a Roman numeral it's CMLXXXI.