256304221 has 2 divisors, whose sum is σ = 256304222. Its totient is φ = 256304220.

The previous prime is 256304219. The next prime is 256304231. The reversal of 256304221 is 122403652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 255648121 + 656100 = 15989^2 + 810^2 .

It is a cyclic number.

It is not a de Polignac number, because 256304221 - 2¹ = 256304219 is a prime.

Together with 256304219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256304231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128152110 + 128152111.

It is an arithmetic number, because the mean of its divisors is an integer number (128152111).

Almost surely, 2^256304221 is an apocalyptic number.

It is an amenable number.

256304221 is a deficient number, since it is larger than the sum of its proper divisors (1).

256304221 is an equidigital number, since it uses as much as digits as its factorization.

256304221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 256304221 is about 16009.5040835124. The cubic root of 256304221 is about 635.2118424365.

Adding to 256304221 its reverse (122403652), we get a palindrome (378707873).

The spelling of 256304221 in words is "two hundred fifty-six million, three hundred four thousand, two hundred twenty-one".