256689869 has 2 divisors, whose sum is σ = 256689870. Its totient is φ = 256689868.

The previous prime is 256689863. The next prime is 256689907. The reversal of 256689869 is 968986652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 252015625 + 4674244 = 15875^2 + 2162^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256689869 is a prime.

It is a super-2 number, since 2×256689869² = 131779377694474322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256689863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128344934 + 128344935.

It is an arithmetic number, because the mean of its divisors is an integer number (128344935).

Almost surely, 2^256689869 is an apocalyptic number.

It is an amenable number.

256689869 is a deficient number, since it is larger than the sum of its proper divisors (1).

256689869 is an equidigital number, since it uses as much as digits as its factorization.

256689869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11197440, while the sum is 59.

The square root of 256689869 is about 16021.5439018841. The cubic root of 256689869 is about 635.5302731599.

The spelling of 256689869 in words is "two hundred fifty-six million, six hundred eighty-nine thousand, eight hundred sixty-nine".