31897681 has 4 divisors (see below), whose sum is σ = 31948864. Its totient is φ = 31846500.

The previous prime is 31897669. The next prime is 31897687. The reversal of 31897681 is 18679813.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 31897681 - 2⁹ = 31897169 is a prime.

It is a super-2 number, since 2×31897681² = 2034924106355522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31897687) 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 in 3 ways as a sum of consecutive naturals, for example, 24645 + ... + 25906.

It is an arithmetic number, because the mean of its divisors is an integer number (7987216).

Almost surely, 2^31897681 is an apocalyptic number.

It is an amenable number.

31897681 is a deficient number, since it is larger than the sum of its proper divisors (51183).

31897681 is an equidigital number, since it uses as much as digits as its factorization.

31897681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51182.

The product of its digits is 72576, while the sum is 43.

The square root of 31897681 is about 5647.8032012456. The cubic root of 31897681 is about 317.1414714171.

The spelling of 31897681 in words is "thirty-one million, eight hundred ninety-seven thousand, six hundred eighty-one".