31161921 has 16 divisors (see below), whose sum is σ = 49123200. Its totient is φ = 17192448.

The previous prime is 31161917. The next prime is 31161959. The reversal of 31161921 is 12916113.

It is not a de Polignac number, because 31161921 - 2² = 31161917 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31161891 and 31161900.

It is not an unprimeable number, because it can be changed into a prime (31161961) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24976 + ... + 26193.

It is an arithmetic number, because the mean of its divisors is an integer number (3070200).

Almost surely, 2^31161921 is an apocalyptic number.

It is an amenable number.

31161921 is a deficient number, since it is larger than the sum of its proper divisors (17961279).

31161921 is a wasteful number, since it uses less digits than its factorization.

31161921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51208.

The product of its digits is 324, while the sum is 24.

The square root of 31161921 is about 5582.2863595484. The cubic root of 31161921 is about 314.6840571151.

The spelling of 31161921 in words is "thirty-one million, one hundred sixty-one thousand, nine hundred twenty-one".