315978921 has 32 divisors (see below), whose sum is σ = 483000320. Its totient is φ = 204038352.

The previous prime is 315978857. The next prime is 315978931. The reversal of 315978921 is 129879513.

315978921 is a `hidden beast` number, since 31 + 597 + 8 + 9 + 21 = 666.

It is not a de Polignac number, because 315978921 - 2⁶ = 315978857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (315978931) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 146376 + ... + 148518.

It is an arithmetic number, because the mean of its divisors is an integer number (15093760).

Almost surely, 2^315978921 is an apocalyptic number.

It is an amenable number.

315978921 is a deficient number, since it is larger than the sum of its proper divisors (167021399).

315978921 is a wasteful number, since it uses less digits than its factorization.

315978921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2322 (or 2316 counting only the distinct ones).

The product of its digits is 136080, while the sum is 45.

The square root of 315978921 is about 17775.7959315469. The cubic root of 315978921 is about 681.1133153827.

The spelling of 315978921 in words is "three hundred fifteen million, nine hundred seventy-eight thousand, nine hundred twenty-one".