172655021 has 12 divisors (see below), whose sum is σ = 216890016. Its totient is φ = 134535720.

The previous prime is 172655011. The next prime is 172655039. The reversal of 172655021 is 120556271.

It is not a de Polignac number, because 172655021 - 2¹⁰ = 172653997 is a prime.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172655011) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 101075 + ... + 102768.

It is an arithmetic number, because the mean of its divisors is an integer number (18074168).

Almost surely, 2^172655021 is an apocalyptic number.

172655021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

172655021 is a deficient number, since it is larger than the sum of its proper divisors (44234995).

172655021 is a wasteful number, since it uses less digits than its factorization.

172655021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203872 (or 203861 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 172655021 is about 13139.8257598798. The cubic root of 172655021 is about 556.8348449428.

The spelling of 172655021 in words is "one hundred seventy-two million, six hundred fifty-five thousand, twenty-one".