256839917 has 2 divisors, whose sum is σ = 256839918. Its totient is φ = 256839916.

The previous prime is 256839907. The next prime is 256839943. The reversal of 256839917 is 719938652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 195468361 + 61371556 = 13981^2 + 7834^2 .

It is a cyclic number.

It is not a de Polignac number, because 256839917 - 2¹⁴ = 256823533 is a prime.

It is a super-3 number, since 3×256839917³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256839907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128419958 + 128419959.

It is an arithmetic number, because the mean of its divisors is an integer number (128419959).

Almost surely, 2^256839917 is an apocalyptic number.

It is an amenable number.

256839917 is a deficient number, since it is larger than the sum of its proper divisors (1).

256839917 is an equidigital number, since it uses as much as digits as its factorization.

256839917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 816480, while the sum is 50.

The square root of 256839917 is about 16026.2259125472. The cubic root of 256839917 is about 635.6540820606.

The spelling of 256839917 in words is "two hundred fifty-six million, eight hundred thirty-nine thousand, nine hundred seventeen".