256220321 has 4 divisors (see below), whose sum is σ = 292823232. Its totient is φ = 219617412.

The previous prime is 256220317. The next prime is 256220333. The reversal of 256220321 is 123022652.

256220321 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 256220321 - 2² = 256220317 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256220351) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18301445 + ... + 18301458.

It is an arithmetic number, because the mean of its divisors is an integer number (73205808).

Almost surely, 2^256220321 is an apocalyptic number.

It is an amenable number.

256220321 is a deficient number, since it is larger than the sum of its proper divisors (36602911).

256220321 is an equidigital number, since it uses as much as digits as its factorization.

256220321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36602910.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 256220321 is about 16006.8835505229. The cubic root of 256220321 is about 635.1425236538.

Adding to 256220321 its reverse (123022652), we get a palindrome (379242973).

The spelling of 256220321 in words is "two hundred fifty-six million, two hundred twenty thousand, three hundred twenty-one".