256778687 has 4 divisors (see below), whose sum is σ = 280122216. Its totient is φ = 233435160.

The previous prime is 256778593. The next prime is 256778713. The reversal of 256778687 is 786877652.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 256778687 - 2²² = 252584383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256718687) 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, 11671748 + ... + 11671769.

It is an arithmetic number, because the mean of its divisors is an integer number (70030554).

Almost surely, 2^256778687 is an apocalyptic number.

256778687 is a deficient number, since it is larger than the sum of its proper divisors (23343529).

256778687 is a wasteful number, since it uses less digits than its factorization.

256778687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23343528.

The product of its digits is 7902720, while the sum is 56.

The square root of 256778687 is about 16024.3154924009. The cubic root of 256778687 is about 635.6035652599.

The spelling of 256778687 in words is "two hundred fifty-six million, seven hundred seventy-eight thousand, six hundred eighty-seven".