256841640 has 192 divisors, whose sum is σ = 923270400. Its totient is φ = 61401600.

The previous prime is 256841633. The next prime is 256841743. The reversal of 256841640 is 46148652.

256841640 is a `hidden beast` number, since 2 + 5 + 6 + 8 + 4 + 1 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 256841595 and 256841604.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 312430 + ... + 313250.

It is an arithmetic number, because the mean of its divisors is an integer number (4808700).

Almost surely, 2^256841640 is an apocalyptic number.

256841640 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 256841640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (461635200).

256841640 is an abundant number, since it is smaller than the sum of its proper divisors (666428760).

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

256841640 is a wasteful number, since it uses less digits than its factorization.

256841640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 928 (or 921 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 256841640 is about 16026.2796680952. The cubic root of 256841640 is about 635.6555034772.

The spelling of 256841640 in words is "two hundred fifty-six million, eight hundred forty-one thousand, six hundred forty".