256511640 has 512 divisors, whose sum is σ = 1074954240. Its totient is φ = 47308800.

The previous prime is 256511611. The next prime is 256511659. The reversal of 256511640 is 46115652.

256511640 = T₁₂₀ + T₁₂₁ + ... + T₁₁₅₄.

256511640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 256511598 and 256511607.

It is a congruent number.

It is an unprimeable number.

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 127 ways as a sum of consecutive naturals, for example, 3612805 + ... + 3612875.

It is an arithmetic number, because the mean of its divisors is an integer number (2099520).

Almost surely, 2^256511640 is an apocalyptic number.

256511640 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 256511640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (537477120).

256511640 is an abundant number, since it is smaller than the sum of its proper divisors (818442600).

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

256511640 is a wasteful number, since it uses less digits than its factorization.

256511640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143 (or 139 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 256511640 is about 16015.9807692192. The cubic root of 256511640 is about 635.3831486013.

The spelling of 256511640 in words is "two hundred fifty-six million, five hundred eleven thousand, six hundred forty".