256126561 has 2 divisors, whose sum is σ = 256126562. Its totient is φ = 256126560.

The previous prime is 256126537. The next prime is 256126571. The reversal of 256126561 is 165621652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 252206161 + 3920400 = 15881^2 + 1980^2 .

It is a cyclic number.

It is not a de Polignac number, because 256126561 - 2¹¹ = 256124513 is a prime.

It is a super-3 number, since 3×256126561³ (a number of 26 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (256126511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128063280 + 128063281.

It is an arithmetic number, because the mean of its divisors is an integer number (128063281).

Almost surely, 2^256126561 is an apocalyptic number.

It is an amenable number.

256126561 is a deficient number, since it is larger than the sum of its proper divisors (1).

256126561 is an equidigital number, since it uses as much as digits as its factorization.

256126561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21600, while the sum is 34.

The square root of 256126561 is about 16003.9545425498. The cubic root of 256126561 is about 635.0650405614.

The spelling of 256126561 in words is "two hundred fifty-six million, one hundred twenty-six thousand, five hundred sixty-one".