256958309 has 2 divisors, whose sum is σ = 256958310. Its totient is φ = 256958308.

The previous prime is 256958243. The next prime is 256958327. The reversal of 256958309 is 903859652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 246395809 + 10562500 = 15697^2 + 3250^2 .

It is a cyclic number.

It is not a de Polignac number, because 256958309 - 2²⁰ = 255909733 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256958389) 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 as a sum of consecutive naturals, namely, 128479154 + 128479155.

It is an arithmetic number, because the mean of its divisors is an integer number (128479155).

Almost surely, 2^256958309 is an apocalyptic number.

It is an amenable number.

256958309 is a deficient number, since it is larger than the sum of its proper divisors (1).

256958309 is an equidigital number, since it uses as much as digits as its factorization.

256958309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 583200, while the sum is 47.

The square root of 256958309 is about 16029.9191825786. The cubic root of 256958309 is about 635.7517366602.

The spelling of 256958309 in words is "two hundred fifty-six million, nine hundred fifty-eight thousand, three hundred nine".