172805128 has 8 divisors (see below), whose sum is σ = 324009630. Its totient is φ = 86402560.

The previous prime is 172805117. The next prime is 172805161. The reversal of 172805128 is 821508271.

It can be written as a sum of positive squares in only one way, i.e., 169989444 + 2815684 = 13038^2 + 1678^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×172805128² = 59723224526192768, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 172805093 and 172805102.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10800313 + ... + 10800328.

Almost surely, 2^172805128 is an apocalyptic number.

It is an amenable number.

172805128 is a deficient number, since it is larger than the sum of its proper divisors (151204502).

172805128 is a wasteful number, since it uses less digits than its factorization.

172805128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21600647 (or 21600643 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 34.

The square root of 172805128 is about 13145.5364287655. The cubic root of 172805128 is about 556.9961697169.

The spelling of 172805128 in words is "one hundred seventy-two million, eight hundred five thousand, one hundred twenty-eight".