31686631 has 2 divisors, whose sum is σ = 31686632. Its totient is φ = 31686630.

The previous prime is 31686587. The next prime is 31686637. The reversal of 31686631 is 13668613.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31686631 is a prime.

It is a super-2 number, since 2×31686631² = 2008085168260322, which contains 22 as substring.

It is equal to p_1955653 and since 31686631 and 1955653 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31686637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15843315 + 15843316.

It is an arithmetic number, because the mean of its divisors is an integer number (15843316).

Almost surely, 2^31686631 is an apocalyptic number.

31686631 is a deficient number, since it is larger than the sum of its proper divisors (1).

31686631 is an equidigital number, since it uses as much as digits as its factorization.

31686631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 34.

The square root of 31686631 is about 5629.0879367798. The cubic root of 31686631 is about 316.4404709070.

The spelling of 31686631 in words is "thirty-one million, six hundred eighty-six thousand, six hundred thirty-one".