256621123332689 has 2 divisors, whose sum is σ = 256621123332690. Its totient is φ = 256621123332688.

The previous prime is 256621123332683. The next prime is 256621123332727. The reversal of 256621123332689 is 986233321126652.

256621123332689 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 241975446913600 + 14645676419089 = 15555560^2 + 3826967^2 .

It is a cyclic number.

It is not a de Polignac number, because 256621123332689 - 2⁴⁰ = 255521611704913 is a prime.

It is not a weakly prime, because it can be changed into another prime (256621123332683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128310561666344 + 128310561666345.

It is an arithmetic number, because the mean of its divisors is an integer number (128310561666345).

Almost surely, 2^{256621123332689} is an apocalyptic number.

It is an amenable number.

256621123332689 is a deficient number, since it is larger than the sum of its proper divisors (1).

256621123332689 is an equidigital number, since it uses as much as digits as its factorization.

256621123332689 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 256621123332689 in words is "two hundred fifty-six trillion, six hundred twenty-one billion, one hundred twenty-three million, three hundred thirty-two thousand, six hundred eighty-nine".