256564621 has 4 divisors (see below), whose sum is σ = 256602492. Its totient is φ = 256526752.

The previous prime is 256564603. The next prime is 256564631. The reversal of 256564621 is 126465652.

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 201952521 + 54612100 = 14211^2 + 7390^2 .

It is a cyclic number.

It is not a de Polignac number, because 256564621 - 2⁵ = 256564589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256564601) 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, 5680 + ... + 23353.

It is an arithmetic number, because the mean of its divisors is an integer number (64150623).

Almost surely, 2^256564621 is an apocalyptic number.

It is an amenable number.

256564621 is a deficient number, since it is larger than the sum of its proper divisors (37871).

256564621 is an equidigital number, since it uses as much as digits as its factorization.

256564621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37870.

The product of its digits is 86400, while the sum is 37.

The square root of 256564621 is about 16017.6346880555. The cubic root of 256564621 is about 635.4268904983.

The spelling of 256564621 in words is "two hundred fifty-six million, five hundred sixty-four thousand, six hundred twenty-one".