256164213521 has 2 divisors, whose sum is σ = 256164213522. Its totient is φ = 256164213520.

The previous prime is 256164213517. The next prime is 256164213553. The reversal of 256164213521 is 125312461652.

256164213521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 248307873025 + 7856340496 = 498305^2 + 88636^2 .

It is a cyclic number.

It is not a de Polignac number, because 256164213521 - 2² = 256164213517 is a prime.

It is not a weakly prime, because it can be changed into another prime (256164213511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128082106760 + 128082106761.

It is an arithmetic number, because the mean of its divisors is an integer number (128082106761).

Almost surely, 2^256164213521 is an apocalyptic number.

It is an amenable number.

256164213521 is a deficient number, since it is larger than the sum of its proper divisors (1).

256164213521 is an equidigital number, since it uses as much as digits as its factorization.

256164213521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 86400, while the sum is 38.

The spelling of 256164213521 in words is "two hundred fifty-six billion, one hundred sixty-four million, two hundred thirteen thousand, five hundred twenty-one".