256665986 has 16 divisors (see below), whose sum is σ = 394836120. Its totient is φ = 125061120.

The previous prime is 256665971. The next prime is 256666031. The reversal of 256665986 is 689566652.

It can be written as a sum of positive squares in 4 ways, for example, as 130530625 + 126135361 = 11425^2 + 11231^2 .

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 134930 + ... + 136818.

Almost surely, 2^256665986 is an apocalyptic number.

256665986 is a deficient number, since it is larger than the sum of its proper divisors (138170134).

256665986 is a wasteful number, since it uses less digits than its factorization.

256665986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3589.

The product of its digits is 4665600, while the sum is 53.

The square root of 256665986 is about 16020.7985443922. The cubic root of 256665986 is about 635.5105621621.

The spelling of 256665986 in words is "two hundred fifty-six million, six hundred sixty-five thousand, nine hundred eighty-six".