Numbers / 105

The Number 105

105 is composite: factorization 3 × 5 × 7. That gives 105 exactly 8 divisors: 1, 3, 5, 7, 15, 21, 35, 105. 105's proper divisors total just 87, 18 short of 105, the deficient case most of 105's neighbors share too. 105 is also the 14th triangular number, the sum of 1 through 14. 105 has a digit sum of 6; for 105, the digital root works out to 6. 105: 3, 5, 7 all divide 105 evenly, out of 2-12. 105 is 1101001 in binary and 69 in hex; as a Roman numeral it's CV.