256257040 has 80 divisors (see below), whose sum is σ = 649958400. Its totient is φ = 93390336.

The previous prime is 256256999. The next prime is 256257049. The reversal of 256257040 is 40752652.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 256256993 and 256257011.

It is not an unprimeable number, because it can be changed into a prime (256257049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 80601 + ... + 83719.

It is an arithmetic number, because the mean of its divisors is an integer number (8124480).

Almost surely, 2^256257040 is an apocalyptic number.

256257040 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 256257040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (324979200).

256257040 is an abundant number, since it is smaller than the sum of its proper divisors (393701360).

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

256257040 is a wasteful number, since it uses less digits than its factorization.

256257040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3224 (or 3218 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 31.

The square root of 256257040 is about 16008.0304847286. The cubic root of 256257040 is about 635.1728630172.

The spelling of 256257040 in words is "two hundred fifty-six million, two hundred fifty-seven thousand, forty".