256747217 has 2 divisors, whose sum is σ = 256747218. Its totient is φ = 256747216.

The previous prime is 256747199. The next prime is 256747223. The reversal of 256747217 is 712747652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 232135696 + 24611521 = 15236^2 + 4961^2 .

It is a cyclic number.

It is not a de Polignac number, because 256747217 - 2¹⁶ = 256681681 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (256747717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128373608 + 128373609.

It is an arithmetic number, because the mean of its divisors is an integer number (128373609).

Almost surely, 2^256747217 is an apocalyptic number.

It is an amenable number.

256747217 is a deficient number, since it is larger than the sum of its proper divisors (1).

256747217 is an equidigital number, since it uses as much as digits as its factorization.

256747217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 164640, while the sum is 41.

The square root of 256747217 is about 16023.3335170931. Note that the first 3 decimals coincide. The cubic root of 256747217 is about 635.5775983314.

The spelling of 256747217 in words is "two hundred fifty-six million, seven hundred forty-seven thousand, two hundred seventeen".