256866187 has 4 divisors (see below), whose sum is σ = 270385480. Its totient is φ = 243346896.

The previous prime is 256866179. The next prime is 256866191. The reversal of 256866187 is 781668652.

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 256866187 - 2³ = 256866179 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 256866187.

It is not an unprimeable number, because it can be changed into a prime (256866157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6759618 + ... + 6759655.

It is an arithmetic number, because the mean of its divisors is an integer number (67596370).

Almost surely, 2^256866187 is an apocalyptic number.

256866187 is a deficient number, since it is larger than the sum of its proper divisors (13519293).

256866187 is a wasteful number, since it uses less digits than its factorization.

256866187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13519292.

The product of its digits is 967680, while the sum is 49.

The square root of 256866187 is about 16027.0454856783. The cubic root of 256866187 is about 635.6757532293.

The spelling of 256866187 in words is "two hundred fifty-six million, eight hundred sixty-six thousand, one hundred eighty-seven".