256645633 has 2 divisors, whose sum is σ = 256645634. Its totient is φ = 256645632.

The previous prime is 256645603. The next prime is 256645667. The reversal of 256645633 is 336546652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 219276864 + 37368769 = 14808^2 + 6113^2 .

It is a cyclic number.

It is not a de Polignac number, because 256645633 - 2⁵ = 256645601 is a prime.

It is not a weakly prime, because it can be changed into another prime (256645603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128322816 + 128322817.

It is an arithmetic number, because the mean of its divisors is an integer number (128322817).

Almost surely, 2^256645633 is an apocalyptic number.

It is an amenable number.

256645633 is a deficient number, since it is larger than the sum of its proper divisors (1).

256645633 is an equidigital number, since it uses as much as digits as its factorization.

256645633 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 388800, while the sum is 40.

The square root of 256645633 is about 16020.1633262586. The cubic root of 256645633 is about 635.4937635612.

The spelling of 256645633 in words is "two hundred fifty-six million, six hundred forty-five thousand, six hundred thirty-three".