256788561 has 16 divisors (see below), whose sum is σ = 353833920. Its totient is φ = 165547200.

The previous prime is 256788541. The next prime is 256788563. The reversal of 256788561 is 165887652.

It is not a de Polignac number, because 256788561 - 2¹⁰ = 256787537 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256788561.

It is not an unprimeable number, because it can be changed into a prime (256788563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3175 + ... + 22883.

It is an arithmetic number, because the mean of its divisors is an integer number (22114620).

Almost surely, 2^256788561 is an apocalyptic number.

It is an amenable number.

256788561 is a deficient number, since it is larger than the sum of its proper divisors (97045359).

256788561 is a wasteful number, since it uses less digits than its factorization.

256788561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19856.

The product of its digits is 806400, while the sum is 48.

The square root of 256788561 is about 16024.6235837226. The cubic root of 256788561 is about 635.6117121836.

Subtracting from 256788561 its reverse (165887652), we obtain a palindrome (90900909).

The spelling of 256788561 in words is "two hundred fifty-six million, seven hundred eighty-eight thousand, five hundred sixty-one".