256448721 has 4 divisors (see below), whose sum is σ = 341931632. Its totient is φ = 170965812.

The previous prime is 256448701. The next prime is 256448741. The reversal of 256448721 is 127844652.

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 an interprime number because it is at equal distance from previous prime (256448701) and next prime (256448741).

It is a de Polignac number, because none of the positive numbers 2^k-256448721 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 256448721.

It is not an unprimeable number, because it can be changed into a prime (256448701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42741451 + ... + 42741456.

It is an arithmetic number, because the mean of its divisors is an integer number (85482908).

Almost surely, 2^256448721 is an apocalyptic number.

It is an amenable number.

256448721 is a deficient number, since it is larger than the sum of its proper divisors (85482911).

256448721 is an equidigital number, since it uses as much as digits as its factorization.

256448721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85482910.

The product of its digits is 107520, while the sum is 39.

The square root of 256448721 is about 16014.0163918987. The cubic root of 256448721 is about 635.3311939201.

The spelling of 256448721 in words is "two hundred fifty-six million, four hundred forty-eight thousand, seven hundred twenty-one".