31997131 has 2 divisors, whose sum is σ = 31997132. Its totient is φ = 31997130.

The previous prime is 31997129. The next prime is 31997137. The reversal of 31997131 is 13179913.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31997131 - 2¹ = 31997129 is a prime.

It is a super-2 number, since 2×31997131² = 2047632784462322, which contains 22 as substring.

Together with 31997129, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31997137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15998565 + 15998566.

It is an arithmetic number, because the mean of its divisors is an integer number (15998566).

Almost surely, 2^31997131 is an apocalyptic number.

31997131 is a deficient number, since it is larger than the sum of its proper divisors (1).

31997131 is an equidigital number, since it uses as much as digits as its factorization.

31997131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5103, while the sum is 34.

The square root of 31997131 is about 5656.6006576388. The cubic root of 31997131 is about 317.4707220817.

The spelling of 31997131 in words is "thirty-one million, nine hundred ninety-seven thousand, one hundred thirty-one".