256521571 has 2 divisors, whose sum is σ = 256521572. Its totient is φ = 256521570.

The previous prime is 256521569. The next prime is 256521593. The reversal of 256521571 is 175125652.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 256521571 - 2¹ = 256521569 is a prime.

Together with 256521569, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (256524571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128260785 + 128260786.

It is an arithmetic number, because the mean of its divisors is an integer number (128260786).

Almost surely, 2^256521571 is an apocalyptic number.

256521571 is a deficient number, since it is larger than the sum of its proper divisors (1).

256521571 is an equidigital number, since it uses as much as digits as its factorization.

256521571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21000, while the sum is 34.

The square root of 256521571 is about 16016.2908003070. The cubic root of 256521571 is about 635.3913482404.

The spelling of 256521571 in words is "two hundred fifty-six million, five hundred twenty-one thousand, five hundred seventy-one".