231521031 has 48 divisors (see below), whose sum is σ = 403104000. Its totient is φ = 130936176.

The previous prime is 231521027. The next prime is 231521057. The reversal of 231521031 is 130125132.

It is not a de Polignac number, because 231521031 - 2² = 231521027 is a prime.

It is a super-2 number, since 2×231521031² = 107203975590605922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 231520995 and 231521013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231521021) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 135420 + ... + 137118.

It is an arithmetic number, because the mean of its divisors is an integer number (8398000).

Almost surely, 2^231521031 is an apocalyptic number.

231521031 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

231521031 is a deficient number, since it is larger than the sum of its proper divisors (171582969).

231521031 is a wasteful number, since it uses less digits than its factorization.

231521031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1825 (or 1812 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 231521031 is about 15215.8151605492. The cubic root of 231521031 is about 614.0402161834.

Adding to 231521031 its reverse (130125132), we get a palindrome (361646163).

The spelling of 231521031 in words is "two hundred thirty-one million, five hundred twenty-one thousand, thirty-one".