231561857 has 2 divisors, whose sum is σ = 231561858. Its totient is φ = 231561856.

The previous prime is 231561853. The next prime is 231561871. The reversal of 231561857 is 758165132.

231561857 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., 227135041 + 4426816 = 15071^2 + 2104^2 .

It is a cyclic number.

It is not a de Polignac number, because 231561857 - 2² = 231561853 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 231561857.

It is not a weakly prime, because it can be changed into another prime (231561851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115780928 + 115780929.

It is an arithmetic number, because the mean of its divisors is an integer number (115780929).

Almost surely, 2^231561857 is an apocalyptic number.

It is an amenable number.

231561857 is a deficient number, since it is larger than the sum of its proper divisors (1).

231561857 is an equidigital number, since it uses as much as digits as its factorization.

231561857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50400, while the sum is 38.

The square root of 231561857 is about 15217.1566660792. The cubic root of 231561857 is about 614.0763069759.

The spelling of 231561857 in words is "two hundred thirty-one million, five hundred sixty-one thousand, eight hundred fifty-seven".