256791280043509 has 2 divisors, whose sum is σ = 256791280043510. Its totient is φ = 256791280043508.

The previous prime is 256791280043489. The next prime is 256791280043569. The reversal of 256791280043509 is 905340082197652.

256791280043509 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., 254199975322500 + 2591304721009 = 15943650^2 + 1609753^2 .

It is a cyclic number.

It is not a de Polignac number, because 256791280043509 - 2²³ = 256791271654901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256791280043569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128395640021754 + 128395640021755.

It is an arithmetic number, because the mean of its divisors is an integer number (128395640021755).

It is a 1-persistent number, because it is pandigital, but 2⋅256791280043509 = 513582560087018 is not.

Almost surely, 2^{256791280043509} is an apocalyptic number.

It is an amenable number.

256791280043509 is a deficient number, since it is larger than the sum of its proper divisors (1).

256791280043509 is an equidigital number, since it uses as much as digits as its factorization.

256791280043509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32659200, while the sum is 61.

The spelling of 256791280043509 in words is "two hundred fifty-six trillion, seven hundred ninety-one billion, two hundred eighty million, forty-three thousand, five hundred nine".