173256561 has 12 divisors (see below), whose sum is σ = 250917888. Its totient is φ = 115200504.

The previous prime is 173256547. The next prime is 173256569. The reversal of 173256561 is 165652371.

173256561 is a `hidden beast` number, since 1 + 7 + 32 + 565 + 61 = 666.

It is not a de Polignac number, because 173256561 - 2¹⁵ = 173223793 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (173256569) 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, 21685 + ... + 28578.

It is an arithmetic number, because the mean of its divisors is an integer number (20909824).

Almost surely, 2^173256561 is an apocalyptic number.

It is an amenable number.

173256561 is a deficient number, since it is larger than the sum of its proper divisors (77661327).

173256561 is a wasteful number, since it uses less digits than its factorization.

173256561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50652 (or 50649 counting only the distinct ones).

The product of its digits is 37800, while the sum is 36.

The square root of 173256561 is about 13162.6958105093. The cubic root of 173256561 is about 557.4807768848.

The spelling of 173256561 in words is "one hundred seventy-three million, two hundred fifty-six thousand, five hundred sixty-one".