256388720 has 40 divisors (see below), whose sum is σ = 681262944. Its totient is φ = 87904512.

The previous prime is 256388687. The next prime is 256388723. The reversal of 256388720 is 27883652.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256388723) 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 7 ways as a sum of consecutive naturals, for example, 228359 + ... + 229478.

Almost surely, 2^256388720 is an apocalyptic number.

256388720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256388720 is an abundant number, since it is smaller than the sum of its proper divisors (424874224).

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

256388720 is a wasteful number, since it uses less digits than its factorization.

256388720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457857 (or 457851 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 41.

The square root of 256388720 is about 16012.1428921928. The cubic root of 256388720 is about 635.2816408292.

The spelling of 256388720 in words is "two hundred fifty-six million, three hundred eighty-eight thousand, seven hundred twenty".