309372921 has 81 divisors (see below), whose sum is σ = 545169261. Its totient is φ = 168854400.

The previous prime is 309372913. The next prime is 309372923. The reversal of 309372921 is 129273903.

The square root of 309372921 is 17589.

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 206066025 + 103306896 = 14355^2 + 10164^2 .

It is not a de Polignac number, because 309372921 - 2³ = 309372913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (309372923) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 7545661 + ... + 7545701.

Almost surely, 2^309372921 is an apocalyptic number.

309372921 is the 17589-th square number.

309372921 is the 8795-th centered octagonal number.

It is an amenable number.

309372921 is a deficient number, since it is larger than the sum of its proper divisors (235796340).

309372921 is a wasteful number, since it uses less digits than its factorization.

309372921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136 (or 68 counting only the distinct ones).

The product of its (nonzero) digits is 20412, while the sum is 36.

The cubic root of 309372921 is about 676.3332922554. Note that the first 3 decimals are identical.

Multiplying 309372921 by its sum of digits (36), we get a square (11137425156 = 105534²).

The spelling of 309372921 in words is "three hundred nine million, three hundred seventy-two thousand, nine hundred twenty-one".