231504561 has 20 divisors (see below), whose sum is σ = 353875632. Its totient is φ = 150744888.

The previous prime is 231504557. The next prime is 231504587. The reversal of 231504561 is 165405132.

It is not a de Polignac number, because 231504561 - 2² = 231504557 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (231504541) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 29751 + ... + 36716.

Almost surely, 2^231504561 is an apocalyptic number.

It is an amenable number.

231504561 is a deficient number, since it is larger than the sum of its proper divisors (122371071).

231504561 is an equidigital number, since it uses as much as digits as its factorization.

231504561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66522 (or 66513 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 231504561 is about 15215.2739377246. The cubic root of 231504561 is about 614.0256552568.

Adding to 231504561 its reverse (165405132), we get a palindrome (396909693).

The spelling of 231504561 in words is "two hundred thirty-one million, five hundred four thousand, five hundred sixty-one".