256791515 has 4 divisors (see below), whose sum is σ = 308149824. Its totient is φ = 205433208.

The previous prime is 256791497. The next prime is 256791529. The reversal of 256791515 is 515197652.

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 256791515 - 2²⁰ = 255742939 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25679147 + ... + 25679156.

It is an arithmetic number, because the mean of its divisors is an integer number (77037456).

Almost surely, 2^256791515 is an apocalyptic number.

256791515 is a deficient number, since it is larger than the sum of its proper divisors (51358309).

256791515 is an equidigital number, since it uses as much as digits as its factorization.

256791515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51358308.

The product of its digits is 94500, while the sum is 41.

The square root of 256791515 is about 16024.7157541093. The cubic root of 256791515 is about 635.6141494544.

The spelling of 256791515 in words is "two hundred fifty-six million, seven hundred ninety-one thousand, five hundred fifteen".