Numbers / 85

The Number 85

85 is composite: factorization 5 × 17. That gives 85 exactly 4 divisors: 1, 5, 17, 85. 85's proper divisors total just 23, 62 short of 85, the deficient case most of 85's neighbors share too. 85 has a digit sum of 13; for 85, the digital root works out to 4. 85: 5 all divide 85 evenly, out of 2-12. 85 is 1010101 in binary and 55 in hex; as a Roman numeral it's LXXXV.