256791280043521 has 4 divisors (see below), whose sum is σ = 263054481995844. Its totient is φ = 250528078091200.

The previous prime is 256791280043509. The next prime is 256791280043569. The reversal of 256791280043521 is 125340082197652.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 57695342105025 + 199095937938496 = 7595745^2 + 14110136^2 .

It is a cyclic number.

It is not a de Polignac number, because 256791280043521 - 2⁵ = 256791280043489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256791280040521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3131600976100 + ... + 3131600976181.

It is an arithmetic number, because the mean of its divisors is an integer number (65763620498961).

It is a 1-persistent number, because it is pandigital, but 2⋅256791280043521 = 513582560087042 is not.

Almost surely, 2^{256791280043521} is an apocalyptic number.

It is an amenable number.

256791280043521 is a deficient number, since it is larger than the sum of its proper divisors (6263201952323).

256791280043521 is an equidigital number, since it uses as much as digits as its factorization.

256791280043521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6263201952322.

The product of its (nonzero) digits is 7257600, while the sum is 55.

The spelling of 256791280043521 in words is "two hundred fifty-six trillion, seven hundred ninety-one billion, two hundred eighty million, forty-three thousand, five hundred twenty-one".