256717291 has 2 divisors, whose sum is σ = 256717292. Its totient is φ = 256717290.

The previous prime is 256717199. The next prime is 256717333. The reversal of 256717291 is 192717652.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256717291 is a prime.

It is not a weakly prime, because it can be changed into another prime (256717891) 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, 128358645 + 128358646.

It is an arithmetic number, because the mean of its divisors is an integer number (128358646).

Almost surely, 2^256717291 is an apocalyptic number.

256717291 is a deficient number, since it is larger than the sum of its proper divisors (1).

256717291 is an equidigital number, since it uses as much as digits as its factorization.

256717291 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52920, while the sum is 40.

The square root of 256717291 is about 16022.3996642201. The cubic root of 256717291 is about 635.5529034396.

The spelling of 256717291 in words is "two hundred fifty-six million, seven hundred seventeen thousand, two hundred ninety-one".