256803661 has 4 divisors (see below), whose sum is σ = 256872672. Its totient is φ = 256734652.

The previous prime is 256803619. The next prime is 256803689. The reversal of 256803661 is 166308652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 256803661 - 2²⁷ = 122585933 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 256803661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256803061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28585 + ... + 36478.

It is an arithmetic number, because the mean of its divisors is an integer number (64218168).

Almost surely, 2^256803661 is an apocalyptic number.

It is an amenable number.

256803661 is a deficient number, since it is larger than the sum of its proper divisors (69011).

256803661 is an equidigital number, since it uses as much as digits as its factorization.

256803661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69010.

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 256803661 is about 16025.0947267091. The cubic root of 256803661 is about 635.6241706160.

The spelling of 256803661 in words is "two hundred fifty-six million, eight hundred three thousand, six hundred sixty-one".