155720172 has 12 divisors (see below), whose sum is σ = 363347096. Its totient is φ = 51906720.

The previous prime is 155720137. The next prime is 155720177. The reversal of 155720172 is 271027551.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (155720177) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6488329 + ... + 6488352.

Almost surely, 2^155720172 is an apocalyptic number.

155720172 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

155720172 is an abundant number, since it is smaller than the sum of its proper divisors (207626924).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

155720172 is a wasteful number, since it uses less digits than its factorization.

155720172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12976688 (or 12976686 counting only the distinct ones).

The product of its (nonzero) digits is 4900, while the sum is 30.

The square root of 155720172 is about 12478.7888835415. The cubic root of 155720172 is about 537.9991938555. Note that the first 3 decimals are identical.

The spelling of 155720172 in words is "one hundred fifty-five million, seven hundred twenty thousand, one hundred seventy-two".