256720128 has 216 divisors, whose sum is σ = 842683968. Its totient is φ = 67731456.

The previous prime is 256720069. The next prime is 256720129. The reversal of 256720128 is 821027652.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256720129) 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 23 ways as a sum of consecutive naturals, for example, 4843750 + ... + 4843802.

Almost surely, 2^256720128 is an apocalyptic number.

256720128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256720128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (421341984).

256720128 is an abundant number, since it is smaller than the sum of its proper divisors (585963840).

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

256720128 is an equidigital number, since it uses as much as digits as its factorization.

256720128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149 (or 82 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 256720128 is about 16022.4881962821. The cubic root of 256720128 is about 635.5552446102. Note that the first 3 decimals are identical.

The spelling of 256720128 in words is "two hundred fifty-six million, seven hundred twenty thousand, one hundred twenty-eight".