256389840 has 320 divisors, whose sum is σ = 1043742720. Its totient is φ = 56609280.

The previous prime is 256389829. The next prime is 256389863. The reversal of 256389840 is 48983652.

256389840 is a `hidden beast` number, since 2 + 5 + 638 + 9 + 8 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 468447 + ... + 468993.

It is an arithmetic number, because the mean of its divisors is an integer number (3261696).

Almost surely, 2^256389840 is an apocalyptic number.

256389840 is a gapful number since it is divisible by the number (20) 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 256389840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (521871360).

256389840 is an abundant number, since it is smaller than the sum of its proper divisors (787352880).

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

256389840 is a wasteful number, since it uses less digits than its factorization.

256389840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607 (or 595 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The square root of 256389840 is about 16012.1778656122. The cubic root of 256389840 is about 635.2825658756.

The spelling of 256389840 in words is "two hundred fifty-six million, three hundred eighty-nine thousand, eight hundred forty".