256442661 has 6 divisors (see below), whose sum is σ = 370417190. Its totient is φ = 170961768.

The previous prime is 256442657. The next prime is 256442687. The reversal of 256442661 is 166244652.

256442661 is a `hidden beast` number, since 2 + 5 + 644 + 2 + 6 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 205033761 + 51408900 = 14319^2 + 7170^2 .

It is not a de Polignac number, because 256442661 - 2² = 256442657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256442561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14246806 + ... + 14246823.

Almost surely, 2^256442661 is an apocalyptic number.

It is an amenable number.

256442661 is a deficient number, since it is larger than the sum of its proper divisors (113974529).

256442661 is a wasteful number, since it uses less digits than its factorization.

256442661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28493635 (or 28493632 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 256442661 is about 16013.8271815328. The cubic root of 256442661 is about 635.3261894923.

The spelling of 256442661 in words is "two hundred fifty-six million, four hundred forty-two thousand, six hundred sixty-one".