256778593 has 2 divisors, whose sum is σ = 256778594. Its totient is φ = 256778592.

The previous prime is 256778579. The next prime is 256778713. The reversal of 256778593 is 395877652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 251634769 + 5143824 = 15863^2 + 2268^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256778593 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256778593.

It is not a weakly prime, because it can be changed into another prime (256778513) 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, 128389296 + 128389297.

It is an arithmetic number, because the mean of its divisors is an integer number (128389297).

Almost surely, 2^256778593 is an apocalyptic number.

It is an amenable number.

256778593 is a deficient number, since it is larger than the sum of its proper divisors (1).

256778593 is an equidigital number, since it uses as much as digits as its factorization.

256778593 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3175200, while the sum is 52.

The square root of 256778593 is about 16024.3125593580. The cubic root of 256778593 is about 635.6034877005.

The spelling of 256778593 in words is "two hundred fifty-six million, seven hundred seventy-eight thousand, five hundred ninety-three".