231500561 has 2 divisors, whose sum is σ = 231500562. Its totient is φ = 231500560.

The previous prime is 231500539. The next prime is 231500597. The reversal of 231500561 is 165005132.

231500561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 225930961 + 5569600 = 15031^2 + 2360^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231500561 is a prime.

It is not a weakly prime, because it can be changed into another prime (231500531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115750280 + 115750281.

It is an arithmetic number, because the mean of its divisors is an integer number (115750281).

Almost surely, 2^231500561 is an apocalyptic number.

It is an amenable number.

231500561 is a deficient number, since it is larger than the sum of its proper divisors (1).

231500561 is an equidigital number, since it uses as much as digits as its factorization.

231500561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 231500561 is about 15215.1424902956. The cubic root of 231500561 is about 614.0221188013.

Adding to 231500561 its reverse (165005132), we get a palindrome (396505693).

The spelling of 231500561 in words is "two hundred thirty-one million, five hundred thousand, five hundred sixty-one".