256820817 has 8 divisors (see below), whose sum is σ = 373557600. Its totient is φ = 155648960.

The previous prime is 256820813. The next prime is 256820821. The reversal of 256820817 is 718028652.

It is an interprime number because it is at equal distance from previous prime (256820813) and next prime (256820821).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 256820817 - 2² = 256820813 is a prime.

It is not an unprimeable number, because it can be changed into a prime (256820813) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3891192 + ... + 3891257.

It is an arithmetic number, because the mean of its divisors is an integer number (46694700).

Almost surely, 2^256820817 is an apocalyptic number.

It is an amenable number.

256820817 is a deficient number, since it is larger than the sum of its proper divisors (116736783).

256820817 is a wasteful number, since it uses less digits than its factorization.

256820817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7782463.

The product of its (nonzero) digits is 53760, while the sum is 39.

The square root of 256820817 is about 16025.6300032167. The cubic root of 256820817 is about 635.6383247826.

The spelling of 256820817 in words is "two hundred fifty-six million, eight hundred twenty thousand, eight hundred seventeen".