172855521 has 24 divisors (see below), whose sum is σ = 264438720. Its totient is φ = 108500256.

The previous prime is 172855489. The next prime is 172855523. The reversal of 172855521 is 125558271.

It is not a de Polignac number, because 172855521 - 2⁵ = 172855489 is a prime.

It is a super-2 number, since 2×172855521² = 59758062280362882, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (172855523) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25531 + ... + 31583.

It is an arithmetic number, because the mean of its divisors is an integer number (11018280).

Almost surely, 2^172855521 is an apocalyptic number.

It is an amenable number.

172855521 is a deficient number, since it is larger than the sum of its proper divisors (91583199).

172855521 is a wasteful number, since it uses less digits than its factorization.

172855521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6245 (or 6242 counting only the distinct ones).

The product of its digits is 28000, while the sum is 36.

The square root of 172855521 is about 13147.4530233046. The cubic root of 172855521 is about 557.0503077322.

The spelling of 172855521 in words is "one hundred seventy-two million, eight hundred fifty-five thousand, five hundred twenty-one".