173189977921 has 9 divisors (see below), whose sum is σ = 173925943849. Its totient is φ = 172457118400.

The previous prime is 173189977913. The next prime is 173189977963. The reversal of 173189977921 is 129779981371.

The square root of 173189977921 is 416161.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 1992640321 + 171197337600 = 44639^2 + 413760^2 .

It is not a de Polignac number, because 173189977921 - 2³ = 173189977913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (173189977321) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 116940501 + ... + 116941981.

Almost surely, 2^173189977921 is an apocalyptic number.

173189977921 is the 416161-st square number.

173189977921 is the 208081-st centered octagonal number.

It is an amenable number.

173189977921 is a deficient number, since it is larger than the sum of its proper divisors (735965928).

173189977921 is an frugal number, since it uses more digits than its factorization.

173189977921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3524 (or 1762 counting only the distinct ones).

The product of its digits is 12002256, while the sum is 64.

Multiplying 173189977921 by its sum of digits (64), we get a square (11084158586944 = 3329288²).

The spelling of 173189977921 in words is "one hundred seventy-three billion, one hundred eighty-nine million, nine hundred seventy-seven thousand, nine hundred twenty-one".