256399128 has 64 divisors (see below), whose sum is σ = 713548800. Its totient is φ = 85307040.

The previous prime is 256399123. The next prime is 256399133. The reversal of 256399128 is 821993652.

256399128 is a `hidden beast` number, since 2 + 5 + 639 + 9 + 1 + 2 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (256399123) and next prime (256399133).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256399123) 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 in 15 ways as a sum of consecutive naturals, for example, 196125 + ... + 197427.

It is an arithmetic number, because the mean of its divisors is an integer number (11149200).

Almost surely, 2^256399128 is an apocalyptic number.

It is an amenable number.

256399128 is an abundant number, since it is smaller than the sum of its proper divisors (457149672).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256399128 is a wasteful number, since it uses less digits than its factorization.

256399128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2229 (or 2219 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 256399128 is about 16012.4678922395. The cubic root of 256399128 is about 635.2902370496.

The spelling of 256399128 in words is "two hundred fifty-six million, three hundred ninety-nine thousand, one hundred twenty-eight".