31197891 has 4 divisors (see below), whose sum is σ = 41597192. Its totient is φ = 20798592.

The previous prime is 31197889. The next prime is 31197893. The reversal of 31197891 is 19879113.

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

It is an interprime number because it is at equal distance from previous prime (31197889) and next prime (31197893).

It is not a de Polignac number, because 31197891 - 2¹ = 31197889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31197893) 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, 5199646 + ... + 5199651.

It is an arithmetic number, because the mean of its divisors is an integer number (10399298).

Almost surely, 2^31197891 is an apocalyptic number.

31197891 is a deficient number, since it is larger than the sum of its proper divisors (10399301).

31197891 is a wasteful number, since it uses less digits than its factorization.

31197891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10399300.

The product of its digits is 13608, while the sum is 39.

The square root of 31197891 is about 5585.5072285335. The cubic root of 31197891 is about 314.8050898022.

The spelling of 31197891 in words is "thirty-one million, one hundred ninety-seven thousand, eight hundred ninety-one".