256221385 has 16 divisors (see below), whose sum is σ = 351760896. Its totient is φ = 175508928.

The previous prime is 256221379. The next prime is 256221419. The reversal of 256221385 is 583122652.

It is not a de Polignac number, because 256221385 - 2⁵ = 256221353 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 256221385.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 35287 + ... + 41923.

It is an arithmetic number, because the mean of its divisors is an integer number (21985056).

Almost surely, 2^256221385 is an apocalyptic number.

It is an amenable number.

256221385 is a deficient number, since it is larger than the sum of its proper divisors (95539511).

256221385 is a wasteful number, since it uses less digits than its factorization.

256221385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7752.

The product of its digits is 28800, while the sum is 34.

The square root of 256221385 is about 16006.9167861897. The cubic root of 256221385 is about 635.1434028329.

The spelling of 256221385 in words is "two hundred fifty-six million, two hundred twenty-one thousand, three hundred eighty-five".