256316220053821 has 2 divisors, whose sum is σ = 256316220053822. Its totient is φ = 256316220053820.

The previous prime is 256316220053759. The next prime is 256316220053849. The reversal of 256316220053821 is 128350022613652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 229134490821721 + 27181729232100 = 15137189^2 + 5213610^2 .

It is a cyclic number.

It is not a de Polignac number, because 256316220053821 - 2¹⁹ = 256316219529533 is a prime.

It is a super-2 number, since 2×256316220053821² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256316220053021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128158110026910 + 128158110026911.

It is an arithmetic number, because the mean of its divisors is an integer number (128158110026911).

Almost surely, 2^{256316220053821} is an apocalyptic number.

It is an amenable number.

256316220053821 is a deficient number, since it is larger than the sum of its proper divisors (1).

256316220053821 is an equidigital number, since it uses as much as digits as its factorization.

256316220053821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1036800, while the sum is 46.

The spelling of 256316220053821 in words is "two hundred fifty-six trillion, three hundred sixteen billion, two hundred twenty million, fifty-three thousand, eight hundred twenty-one".