256486561 has 2 divisors, whose sum is σ = 256486562. Its totient is φ = 256486560.

The previous prime is 256486537. The next prime is 256486613. The reversal of 256486561 is 165684652.

256486561 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., 225750625 + 30735936 = 15025^2 + 5544^2 .

It is a cyclic number.

It is not a de Polignac number, because 256486561 - 2²⁷ = 122268833 is a prime.

It is not a weakly prime, because it can be changed into another prime (256286561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128243280 + 128243281.

It is an arithmetic number, because the mean of its divisors is an integer number (128243281).

Almost surely, 2^256486561 is an apocalyptic number.

It is an amenable number.

256486561 is a deficient number, since it is larger than the sum of its proper divisors (1).

256486561 is an equidigital number, since it uses as much as digits as its factorization.

256486561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 345600, while the sum is 43.

The square root of 256486561 is about 16015.1978133272. The cubic root of 256486561 is about 635.3624409078.

The spelling of 256486561 in words is "two hundred fifty-six million, four hundred eighty-six thousand, five hundred sixty-one".