31561631 has 2 divisors, whose sum is σ = 31561632. Its totient is φ = 31561630.

The previous prime is 31561597. The next prime is 31561643. The reversal of 31561631 is 13616513.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31561631 is a prime.

It is a super-2 number, since 2×31561631² = 1992273102760322, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31561631.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31561661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15780815 + 15780816.

It is an arithmetic number, because the mean of its divisors is an integer number (15780816).

Almost surely, 2^31561631 is an apocalyptic number.

31561631 is a deficient number, since it is larger than the sum of its proper divisors (1).

31561631 is an equidigital number, since it uses as much as digits as its factorization.

31561631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1620, while the sum is 26.

The square root of 31561631 is about 5617.9739230438. The cubic root of 31561631 is about 316.0238158358.

The spelling of 31561631 in words is "thirty-one million, five hundred sixty-one thousand, six hundred thirty-one".