256616643389 has 2 divisors, whose sum is σ = 256616643390. Its totient is φ = 256616643388.

The previous prime is 256616643331. The next prime is 256616643397. The reversal of 256616643389 is 983346616652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 235548120889 + 21068522500 = 485333^2 + 145150^2 .

It is a cyclic number.

It is not a de Polignac number, because 256616643389 - 2⁸ = 256616643133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256616640389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128308321694 + 128308321695.

It is an arithmetic number, because the mean of its divisors is an integer number (128308321695).

Almost surely, 2^256616643389 is an apocalyptic number.

It is an amenable number.

256616643389 is a deficient number, since it is larger than the sum of its proper divisors (1).

256616643389 is an equidigital number, since it uses as much as digits as its factorization.

256616643389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 33592320, while the sum is 59.

The spelling of 256616643389 in words is "two hundred fifty-six billion, six hundred sixteen million, six hundred forty-three thousand, three hundred eighty-nine".