256638834 has 64 divisors (see below), whose sum is σ = 613889280. Its totient is φ = 79176960.

The previous prime is 256638829. The next prime is 256638841. The reversal of 256638834 is 438836652.

It is a happy number.

256638834 is a `hidden beast` number, since 2 + 5 + 6 + 638 + 8 + 3 + 4 = 666.

It is a super-2 number, since 2×256638834² = 131726982233759112, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 256638834.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 53707 + ... + 58289.

It is an arithmetic number, because the mean of its divisors is an integer number (9592020).

Almost surely, 2^256638834 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256638834, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (306944640).

256638834 is an abundant number, since it is smaller than the sum of its proper divisors (357250446).

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

256638834 is a wasteful number, since it uses less digits than its factorization.

256638834 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4672 (or 4666 counting only the distinct ones).

The product of its digits is 829440, while the sum is 45.

The square root of 256638834 is about 16019.9511235209. The cubic root of 256638834 is about 635.4881517244.

The spelling of 256638834 in words is "two hundred fifty-six million, six hundred thirty-eight thousand, eight hundred thirty-four".