256753056251721 has 4 divisors (see below), whose sum is σ = 342337408335632. Its totient is φ = 171168704167812.

The previous prime is 256753056251717. The next prime is 256753056251723. The reversal of 256753056251721 is 127152650357652.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 256753056251721 - 2² = 256753056251717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256753056251723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42792176041951 + ... + 42792176041956.

It is an arithmetic number, because the mean of its divisors is an integer number (85584352083908).

Almost surely, 2^{256753056251721} is an apocalyptic number.

It is an amenable number.

256753056251721 is a deficient number, since it is larger than the sum of its proper divisors (85584352083911).

256753056251721 is an equidigital number, since it uses as much as digits as its factorization.

256753056251721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85584352083910.

The product of its (nonzero) digits is 26460000, while the sum is 57.

The spelling of 256753056251721 in words is "two hundred fifty-six trillion, seven hundred fifty-three billion, fifty-six million, two hundred fifty-one thousand, seven hundred twenty-one".