20131931 has 2 divisors, whose sum is σ = 20131932. Its totient is φ = 20131930.

The previous prime is 20131919. The next prime is 20131939. The reversal of 20131931 is 13913102.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20131931 is a prime.

It is a super-2 number, since 2×20131931² = 810589291577522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20131939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10065965 + 10065966.

It is an arithmetic number, because the mean of its divisors is an integer number (10065966).

Almost surely, 2^20131931 is an apocalyptic number.

20131931 is a deficient number, since it is larger than the sum of its proper divisors (1).

20131931 is an equidigital number, since it uses as much as digits as its factorization.

20131931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162, while the sum is 20.

The square root of 20131931 is about 4486.8620437896. The cubic root of 20131931 is about 272.0373137607.

The spelling of 20131931 in words is "twenty million, one hundred thirty-one thousand, nine hundred thirty-one".