256509635209 has 2 divisors, whose sum is σ = 256509635210. Its totient is φ = 256509635208.

The previous prime is 256509635183. The next prime is 256509635243. The reversal of 256509635209 is 902536905652.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 169082972809 + 87426662400 = 411197^2 + 295680^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256509635209 is a prime.

It is not a weakly prime, because it can be changed into another prime (256509635269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128254817604 + 128254817605.

It is an arithmetic number, because the mean of its divisors is an integer number (128254817605).

Almost surely, 2^256509635209 is an apocalyptic number.

It is an amenable number.

256509635209 is a deficient number, since it is larger than the sum of its proper divisors (1).

256509635209 is an equidigital number, since it uses as much as digits as its factorization.

256509635209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4374000, while the sum is 52.

The spelling of 256509635209 in words is "two hundred fifty-six billion, five hundred nine million, six hundred thirty-five thousand, two hundred nine".