231011531 has 4 divisors (see below), whose sum is σ = 231740592. Its totient is φ = 230282472.

The previous prime is 231011509. The next prime is 231011569. The reversal of 231011531 is 135110132.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231011531 is a prime.

It is a super-2 number, since 2×231011531² = 106732654909927922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231011591) 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, 364055 + ... + 364688.

It is an arithmetic number, because the mean of its divisors is an integer number (57935148).

Almost surely, 2^231011531 is an apocalyptic number.

231011531 is a deficient number, since it is larger than the sum of its proper divisors (729061).

231011531 is an equidigital number, since it uses as much as digits as its factorization.

231011531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729060.

The product of its (nonzero) digits is 90, while the sum is 17.

The square root of 231011531 is about 15199.0634908865. The cubic root of 231011531 is about 613.5894532945.

Adding to 231011531 its reverse (135110132), we get a palindrome (366121663).

The spelling of 231011531 in words is "two hundred thirty-one million, eleven thousand, five hundred thirty-one".