256680517 has 8 divisors (see below), whose sum is σ = 259297560. Its totient is φ = 254069760.

The previous prime is 256680511. The next prime is 256680533. The reversal of 256680517 is 715086652.

It can be written as a sum of positive squares in 4 ways, for example, as 2405601 + 254274916 = 1551^2 + 15946^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256680517 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 256680517.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256680511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152959 + ... + 154627.

It is an arithmetic number, because the mean of its divisors is an integer number (32412195).

Almost surely, 2^256680517 is an apocalyptic number.

It is an amenable number.

256680517 is a deficient number, since it is larger than the sum of its proper divisors (2617043).

256680517 is a wasteful number, since it uses less digits than its factorization.

256680517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3143.

The product of its (nonzero) digits is 100800, while the sum is 40.

The square root of 256680517 is about 16021.2520422094. The cubic root of 256680517 is about 635.5225549598.

The spelling of 256680517 in words is "two hundred fifty-six million, six hundred eighty thousand, five hundred seventeen".