256639388 has 12 divisors (see below), whose sum is σ = 452134200. Its totient is φ = 127458192.

The previous prime is 256639387. The next prime is 256639391. The reversal of 256639388 is 883936652.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256639387) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 214706 + ... + 215897.

It is an arithmetic number, because the mean of its divisors is an integer number (37677850).

Almost surely, 2^256639388 is an apocalyptic number.

It is an amenable number.

256639388 is a deficient number, since it is larger than the sum of its proper divisors (195494812).

256639388 is a wasteful number, since it uses less digits than its factorization.

256639388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430756 (or 430754 counting only the distinct ones).

The product of its digits is 1866240, while the sum is 50.

The square root of 256639388 is about 16019.9684144508. The cubic root of 256639388 is about 635.4886089950.

The spelling of 256639388 in words is "two hundred fifty-six million, six hundred thirty-nine thousand, three hundred eighty-eight".