256927818221 has 2 divisors, whose sum is σ = 256927818222. Its totient is φ = 256927818220.

The previous prime is 256927818179. The next prime is 256927818227. The reversal of 256927818221 is 122818729652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 239698368100 + 17229450121 = 489590^2 + 131261^2 .

It is a cyclic number.

It is not a de Polignac number, because 256927818221 - 2⁶ = 256927818157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256927818227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128463909110 + 128463909111.

It is an arithmetic number, because the mean of its divisors is an integer number (128463909111).

Almost surely, 2^256927818221 is an apocalyptic number.

It is an amenable number.

256927818221 is a deficient number, since it is larger than the sum of its proper divisors (1).

256927818221 is an equidigital number, since it uses as much as digits as its factorization.

256927818221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1935360, while the sum is 53.

The spelling of 256927818221 in words is "two hundred fifty-six billion, nine hundred twenty-seven million, eight hundred eighteen thousand, two hundred twenty-one".