256401866 has 8 divisors (see below), whose sum is σ = 439546080. Its totient is φ = 109886508.

The previous prime is 256401841. The next prime is 256401877. The reversal of 256401866 is 668104652.

It is a sphenic number, since it is the product of 3 distinct primes.

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 3 ways as a sum of consecutive naturals, for example, 9157196 + ... + 9157223.

It is an arithmetic number, because the mean of its divisors is an integer number (54943260).

Almost surely, 2^256401866 is an apocalyptic number.

256401866 is a deficient number, since it is larger than the sum of its proper divisors (183144214).

256401866 is a wasteful number, since it uses less digits than its factorization.

256401866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18314428.

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 256401866 is about 16012.5533878891. The cubic root of 256401866 is about 635.2924983918.

The spelling of 256401866 in words is "two hundred fifty-six million, four hundred one thousand, eight hundred sixty-six".