31899891 has 4 divisors (see below), whose sum is σ = 42533192. Its totient is φ = 21266592.

The previous prime is 31899877. The next prime is 31899893. The reversal of 31899891 is 19899813.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 31899891 - 2⁹ = 31899379 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31899891.

It is not an unprimeable number, because it can be changed into a prime (31899893) 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, 5316646 + ... + 5316651.

It is an arithmetic number, because the mean of its divisors is an integer number (10633298).

Almost surely, 2^31899891 is an apocalyptic number.

31899891 is a deficient number, since it is larger than the sum of its proper divisors (10633301).

31899891 is a wasteful number, since it uses less digits than its factorization.

31899891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10633300.

The product of its digits is 139968, while the sum is 48.

The square root of 31899891 is about 5647.9988491500. The cubic root of 31899891 is about 317.1487955281.

The spelling of 31899891 in words is "thirty-one million, eight hundred ninety-nine thousand, eight hundred ninety-one".