20309931 has 12 divisors (see below), whose sum is σ = 29377920. Its totient is φ = 13520880.

The previous prime is 20309923. The next prime is 20309941. The reversal of 20309931 is 13990302.

It is not a de Polignac number, because 20309931 - 2³ = 20309923 is a prime.

It is a super-2 number, since 2×20309931² = 824986594449522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 20309895 and 20309904.

It is not an unprimeable number, because it can be changed into a prime (20309921) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8566 + ... + 10676.

It is an arithmetic number, because the mean of its divisors is an integer number (2448160).

Almost surely, 2^20309931 is an apocalyptic number.

20309931 is a deficient number, since it is larger than the sum of its proper divisors (9067989).

20309931 is a wasteful number, since it uses less digits than its factorization.

20309931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3186 (or 3183 counting only the distinct ones).

The product of its (nonzero) digits is 1458, while the sum is 27.

The square root of 20309931 is about 4506.6540803572. The cubic root of 20309931 is about 272.8367175590.

The spelling of 20309931 in words is "twenty million, three hundred nine thousand, nine hundred thirty-one".