Numbers / 155

The Number 155

155 is composite: factorization 5 × 31. That gives 155 exactly 4 divisors: 1, 5, 31, 155. 155's proper divisors total just 37, 118 short of 155, the deficient case most of 155's neighbors share too. 155 has a digit sum of 11; for 155, the digital root works out to 2. 155: 5 all divide 155 evenly, out of 2-12. 155 is 10011011 in binary and 9B in hex; as a Roman numeral it's CLV.