256636769 has 2 divisors, whose sum is σ = 256636770. Its totient is φ = 256636768.

The previous prime is 256636739. The next prime is 256636789. The reversal of 256636769 is 967636652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 192876544 + 63760225 = 13888^2 + 7985^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256636769 is a prime.

It is a super-2 number, since 2×256636769² = 131724862405518722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (256636739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128318384 + 128318385.

It is an arithmetic number, because the mean of its divisors is an integer number (128318385).

Almost surely, 2^256636769 is an apocalyptic number.

It is an amenable number.

256636769 is a deficient number, since it is larger than the sum of its proper divisors (1).

256636769 is an equidigital number, since it uses as much as digits as its factorization.

256636769 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2449440, while the sum is 50.

The square root of 256636769 is about 16019.8866725080. The cubic root of 256636769 is about 635.4864472713.

The spelling of 256636769 in words is "two hundred fifty-six million, six hundred thirty-six thousand, seven hundred sixty-nine".