231916561 has 4 divisors (see below), whose sum is σ = 231996400. Its totient is φ = 231836724.

The previous prime is 231916537. The next prime is 231916583. The reversal of 231916561 is 165619132.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 231916561 - 2¹⁵ = 231883793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231916661) 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, 35391 + ... + 41428.

It is an arithmetic number, because the mean of its divisors is an integer number (57999100).

Almost surely, 2^231916561 is an apocalyptic number.

It is an amenable number.

231916561 is a deficient number, since it is larger than the sum of its proper divisors (79839).

231916561 is an equidigital number, since it uses as much as digits as its factorization.

231916561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79838.

The product of its digits is 9720, while the sum is 34.

The square root of 231916561 is about 15228.8069460480. The cubic root of 231916561 is about 614.3896922113.

The spelling of 231916561 in words is "two hundred thirty-one million, nine hundred sixteen thousand, five hundred sixty-one".