231031521 has 36 divisors (see below), whose sum is σ = 402594192. Its totient is φ = 132011208.

The previous prime is 231031453. The next prime is 231031531. The reversal of 231031521 is 125130132.

It is not a de Polignac number, because 231031521 - 2¹⁰ = 231030497 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 231031494 and 231031503.

It is not an unprimeable number, because it can be changed into a prime (231031531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2206 + ... + 21608.

It is an arithmetic number, because the mean of its divisors is an integer number (11183172).

Almost surely, 2^231031521 is an apocalyptic number.

231031521 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

231031521 is a deficient number, since it is larger than the sum of its proper divisors (171562671).

231031521 is an equidigital number, since it uses as much as digits as its factorization.

231031521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19432 (or 19413 counting only the distinct ones).

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

The square root of 231031521 is about 15199.7210829673. The cubic root of 231031521 is about 613.6071512558.

Adding to 231031521 its reverse (125130132), we get a palindrome (356161653).

The spelling of 231031521 in words is "two hundred thirty-one million, thirty-one thousand, five hundred twenty-one".