Numbers / 161

The Number 161

161 is composite: factorization 7 × 23. That gives 161 exactly 4 divisors: 1, 7, 23, 161. 161's proper divisors total just 31, 130 short of 161, the deficient case most of 161's neighbors share too. 161 is also a palindrome, since 161 reads identically forwards and backwards. 161 has a digit sum of 8; for 161, the digital root works out to 8. 161: 7 all divide 161 evenly, out of 2-12. 161 is 10100001 in binary and A1 in hex; as a Roman numeral it's CLXI.