231331531 has 2 divisors, whose sum is σ = 231331532. Its totient is φ = 231331530.

The previous prime is 231331523. The next prime is 231331571. The reversal of 231331531 is 135133132.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 231331531 - 2³ = 231331523 is a prime.

It is a super-2 number, since 2×231331531² = 107028554469607922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (231331571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115665765 + 115665766.

It is an arithmetic number, because the mean of its divisors is an integer number (115665766).

Almost surely, 2^231331531 is an apocalyptic number.

231331531 is a deficient number, since it is larger than the sum of its proper divisors (1).

231331531 is an equidigital number, since it uses as much as digits as its factorization.

231331531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 810, while the sum is 22.

The square root of 231331531 is about 15209.5868122707. The cubic root of 231331531 is about 613.8726397837.

Adding to 231331531 its reverse (135133132), we get a palindrome (366464663).

The spelling of 231331531 in words is "two hundred thirty-one million, three hundred thirty-one thousand, five hundred thirty-one".