31213939 has 2 divisors, whose sum is σ = 31213940. Its totient is φ = 31213938.

The previous prime is 31213913. The next prime is 31213957. The reversal of 31213939 is 93931213.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31213939 - 2¹¹ = 31211891 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31213939.

It is not a weakly prime, because it can be changed into another prime (31213999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15606969 + 15606970.

It is an arithmetic number, because the mean of its divisors is an integer number (15606970).

Almost surely, 2^31213939 is an apocalyptic number.

31213939 is a deficient number, since it is larger than the sum of its proper divisors (1).

31213939 is an equidigital number, since it uses as much as digits as its factorization.

31213939 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4374, while the sum is 31.

The square root of 31213939 is about 5586.9436188313. The cubic root of 31213939 is about 314.8590584726.

The spelling of 31213939 in words is "thirty-one million, two hundred thirteen thousand, nine hundred thirty-nine".