31997913 has 4 divisors (see below), whose sum is σ = 42663888. Its totient is φ = 21331940.

The previous prime is 31997909. The next prime is 31997963. The reversal of 31997913 is 31979913.

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 31997913 - 2² = 31997909 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31997963) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5332983 + ... + 5332988.

It is an arithmetic number, because the mean of its divisors is an integer number (10665972).

Almost surely, 2^31997913 is an apocalyptic number.

It is an amenable number.

31997913 is a deficient number, since it is larger than the sum of its proper divisors (10665975).

31997913 is a wasteful number, since it uses less digits than its factorization.

31997913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10665974.

The product of its digits is 45927, while the sum is 42.

The square root of 31997913 is about 5656.6697800031. The cubic root of 31997913 is about 317.4733083561.

The spelling of 31997913 in words is "thirty-one million, nine hundred ninety-seven thousand, nine hundred thirteen".