31639961 has 2 divisors, whose sum is σ = 31639962. Its totient is φ = 31639960.

The previous prime is 31639939. The next prime is 31639963. The reversal of 31639961 is 16993613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18361225 + 13278736 = 4285^2 + 3644^2 .

It is a cyclic number.

It is not a de Polignac number, because 31639961 - 2²² = 27445657 is a prime.

Together with 31639963, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31639963) 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, 15819980 + 15819981.

It is an arithmetic number, because the mean of its divisors is an integer number (15819981).

Almost surely, 2^31639961 is an apocalyptic number.

It is an amenable number.

31639961 is a deficient number, since it is larger than the sum of its proper divisors (1).

31639961 is an equidigital number, since it uses as much as digits as its factorization.

31639961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26244, while the sum is 38.

The square root of 31639961 is about 5624.9409774681. The cubic root of 31639961 is about 316.2850369718.

The spelling of 31639961 in words is "thirty-one million, six hundred thirty-nine thousand, nine hundred sixty-one".