256121606281 has 2 divisors, whose sum is σ = 256121606282. Its totient is φ = 256121606280.

The previous prime is 256121606249. The next prime is 256121606287. The reversal of 256121606281 is 182606121652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 245479620681 + 10641985600 = 495459^2 + 103160^2 .

It is a cyclic number.

It is not a de Polignac number, because 256121606281 - 2⁵ = 256121606249 is a prime.

It is a super-2 number, since 2×256121606281² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (256121606287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128060803140 + 128060803141.

It is an arithmetic number, because the mean of its divisors is an integer number (128060803141).

Almost surely, 2^256121606281 is an apocalyptic number.

It is an amenable number.

256121606281 is a deficient number, since it is larger than the sum of its proper divisors (1).

256121606281 is an equidigital number, since it uses as much as digits as its factorization.

256121606281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69120, while the sum is 40.

The spelling of 256121606281 in words is "two hundred fifty-six billion, one hundred twenty-one million, six hundred six thousand, two hundred eighty-one".