31939681 has 2 divisors, whose sum is σ = 31939682. Its totient is φ = 31939680.

The previous prime is 31939679. The next prime is 31939693. The reversal of 31939681 is 18693913.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29430625 + 2509056 = 5425^2 + 1584^2 .

It is a cyclic number.

It is not a de Polignac number, because 31939681 - 2¹ = 31939679 is a prime.

It is a super-2 number, since 2×31939681² = 2040286444763522, which contains 22 as substring.

Together with 31939679, 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 (31939181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15969840 + 15969841.

It is an arithmetic number, because the mean of its divisors is an integer number (15969841).

Almost surely, 2^31939681 is an apocalyptic number.

It is an amenable number.

31939681 is a deficient number, since it is larger than the sum of its proper divisors (1).

31939681 is an equidigital number, since it uses as much as digits as its factorization.

31939681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 40.

The square root of 31939681 is about 5651.5202379537. The cubic root of 31939681 is about 317.2806048325.

It can be divided in two parts, 319 and 39681, that added together give a square (40000 = 200²).

The spelling of 31939681 in words is "thirty-one million, nine hundred thirty-nine thousand, six hundred eighty-one".