231712561 has 4 divisors (see below), whose sum is σ = 231934500. Its totient is φ = 231490624.

The previous prime is 231712493. The next prime is 231712597. The reversal of 231712561 is 165217132.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 96432400 + 135280161 = 9820^2 + 11631^2 .

It is a cyclic number.

It is not a de Polignac number, because 231712561 - 2¹⁵ = 231679793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231718561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109396 + ... + 111493.

It is an arithmetic number, because the mean of its divisors is an integer number (57983625).

Almost surely, 2^231712561 is an apocalyptic number.

It is an amenable number.

231712561 is a deficient number, since it is larger than the sum of its proper divisors (221939).

231712561 is a wasteful number, since it uses less digits than its factorization.

231712561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221938.

The product of its digits is 2520, while the sum is 28.

The square root of 231712561 is about 15222.1076398769. The cubic root of 231712561 is about 614.2094948390.

Adding to 231712561 its reverse (165217132), we get a palindrome (396929693).

It can be divided in two parts, 2317 and 12561, that added together give a triangular number (14878 = T₁₇₂).

The spelling of 231712561 in words is "two hundred thirty-one million, seven hundred twelve thousand, five hundred sixty-one".