31131491 has 4 divisors (see below), whose sum is σ = 31186584. Its totient is φ = 31076400.

The previous prime is 31131487. The next prime is 31131493. The reversal of 31131491 is 19413113.

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

It is a cyclic number.

It is not a de Polignac number, because 31131491 - 2² = 31131487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31131493) 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, 26690 + ... + 27831.

It is an arithmetic number, because the mean of its divisors is an integer number (7796646).

Almost surely, 2^31131491 is an apocalyptic number.

31131491 is a deficient number, since it is larger than the sum of its proper divisors (55093).

31131491 is an equidigital number, since it uses as much as digits as its factorization.

31131491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55092.

The product of its digits is 324, while the sum is 23.

The square root of 31131491 is about 5579.5601081089. The cubic root of 31131491 is about 314.5815928016.

The spelling of 31131491 in words is "thirty-one million, one hundred thirty-one thousand, four hundred ninety-one".