256309240 has 256 divisors, whose sum is σ = 729907200. Its totient is φ = 79833600.

The previous prime is 256309223. The next prime is 256309243. The reversal of 256309240 is 42903652.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256309243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5960659 + ... + 5960701.

It is an arithmetic number, because the mean of its divisors is an integer number (2851200).

Almost surely, 2^256309240 is an apocalyptic number.

256309240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

256309240 is the 13072-nd pentagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256309240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (364953600).

256309240 is an abundant number, since it is smaller than the sum of its proper divisors (473597960).

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

256309240 is a wasteful number, since it uses less digits than its factorization.

256309240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138 (or 134 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 256309240 is about 16009.6608333843. The cubic root of 256309240 is about 635.2159886908.

The spelling of 256309240 in words is "two hundred fifty-six million, three hundred nine thousand, two hundred forty".