256744421705665 has 16 divisors (see below), whose sum is σ = 324730745485200. Its totient is φ = 194571179176192.

The previous prime is 256744421705657. The next prime is 256744421705677. The reversal of 256744421705665 is 566507124447652.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 26085115954881 + 230659305750784 = 5107359^2 + 15187472^2 .

It is a cyclic number.

It is not a de Polignac number, because 256744421705665 - 2³ = 256744421705657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 256744421705597 and 256744421705606.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16704248770 + ... + 16704264139.

It is an arithmetic number, because the mean of its divisors is an integer number (20295671592825).

Almost surely, 2^{256744421705665} is an apocalyptic number.

It is an amenable number.

256744421705665 is a deficient number, since it is larger than the sum of its proper divisors (67986323779535).

256744421705665 is a wasteful number, since it uses less digits than its factorization.

256744421705665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33408512996.

The product of its (nonzero) digits is 338688000, while the sum is 64.

The spelling of 256744421705665 in words is "two hundred fifty-six trillion, seven hundred forty-four billion, four hundred twenty-one million, seven hundred five thousand, six hundred sixty-five".