31561939 has 2 divisors, whose sum is σ = 31561940. Its totient is φ = 31561938.

The previous prime is 31561927. The next prime is 31561967. The reversal of 31561939 is 93916513.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31561939 - 2⁷ = 31561811 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 31561898 and 31561907.

It is not a weakly prime, because it can be changed into another prime (31561919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15780969 + 15780970.

It is an arithmetic number, because the mean of its divisors is an integer number (15780970).

Almost surely, 2^31561939 is an apocalyptic number.

31561939 is a deficient number, since it is larger than the sum of its proper divisors (1).

31561939 is an equidigital number, since it uses as much as digits as its factorization.

31561939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21870, while the sum is 37.

The square root of 31561939 is about 5618.0013349945. The cubic root of 31561939 is about 316.0248438247.

The spelling of 31561939 in words is "thirty-one million, five hundred sixty-one thousand, nine hundred thirty-nine".