256817239 has 4 divisors (see below), whose sum is σ = 293505424. Its totient is φ = 220129056.

The previous prime is 256817221. The next prime is 256817257. The reversal of 256817239 is 932718652.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (256817221) and next prime (256817257).

It is not a de Polignac number, because 256817239 - 2¹⁵ = 256784471 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 256817195 and 256817204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256817219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18344082 + ... + 18344095.

It is an arithmetic number, because the mean of its divisors is an integer number (73376356).

Almost surely, 2^256817239 is an apocalyptic number.

256817239 is a deficient number, since it is larger than the sum of its proper divisors (36688185).

256817239 is an equidigital number, since it uses as much as digits as its factorization.

256817239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36688184.

The product of its digits is 181440, while the sum is 43.

The square root of 256817239 is about 16025.5183691511. The cubic root of 256817239 is about 635.6353728873.

The spelling of 256817239 in words is "two hundred fifty-six million, eight hundred seventeen thousand, two hundred thirty-nine".