256039691 has 4 divisors (see below), whose sum is σ = 261487392. Its totient is φ = 250591992.

The previous prime is 256039681. The next prime is 256039709. The reversal of 256039691 is 196930652.

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 256039691 - 2⁶ = 256039627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256039681) 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, 2723780 + ... + 2723873.

It is an arithmetic number, because the mean of its divisors is an integer number (65371848).

Almost surely, 2^256039691 is an apocalyptic number.

256039691 is a deficient number, since it is larger than the sum of its proper divisors (5447701).

256039691 is an equidigital number, since it uses as much as digits as its factorization.

256039691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5447700.

The product of its (nonzero) digits is 87480, while the sum is 41.

The square root of 256039691 is about 16001.2402956771. The cubic root of 256039691 is about 634.9932344744.

The spelling of 256039691 in words is "two hundred fifty-six million, thirty-nine thousand, six hundred ninety-one".