178792819921 has 9 divisors (see below), whose sum is σ = 180862368283. Its totient is φ = 176746702000.

The previous prime is 178792819873. The next prime is 178792819927. The reversal of 178792819921 is 129918297871.

The square root of 178792819921 is 422839.

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

It can be written as a sum of positive squares in only one way, i.e., 34332013521 + 144460806400 = 185289^2 + 380080^2 .

It is not a de Polignac number, because 178792819921 - 2²¹ = 178790722769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (178792819927) 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, 37630296 + ... + 37635046.

Almost surely, 2^178792819921 is an apocalyptic number.

178792819921 is the 422839-th square number.

178792819921 is the 211420-th centered octagonal number.

It is an amenable number.

178792819921 is a deficient number, since it is larger than the sum of its proper divisors (2069548362).

178792819921 is an frugal number, since it uses more digits than its factorization.

178792819921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9680 (or 4840 counting only the distinct ones).

The product of its digits is 9144576, while the sum is 64.

Multiplying 178792819921 by its sum of digits (64), we get a square (11442740474944 = 3382712²).

The spelling of 178792819921 in words is "one hundred seventy-eight billion, seven hundred ninety-two million, eight hundred nineteen thousand, nine hundred twenty-one".