256475909 has 2 divisors, whose sum is σ = 256475910. Its totient is φ = 256475908.

The previous prime is 256475899. The next prime is 256475929. The reversal of 256475909 is 909574652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 219691684 + 36784225 = 14822^2 + 6065^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256475909 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256475929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128237954 + 128237955.

It is an arithmetic number, because the mean of its divisors is an integer number (128237955).

Almost surely, 2^256475909 is an apocalyptic number.

It is an amenable number.

256475909 is a deficient number, since it is larger than the sum of its proper divisors (1).

256475909 is an equidigital number, since it uses as much as digits as its factorization.

256475909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 680400, while the sum is 47.

The square root of 256475909 is about 16014.8652507600. The cubic root of 256475909 is about 635.3536451585.

The spelling of 256475909 in words is "two hundred fifty-six million, four hundred seventy-five thousand, nine hundred nine".