256381638 has 16 divisors (see below), whose sum is σ = 513010416. Its totient is φ = 85419360.

The previous prime is 256381633. The next prime is 256381673. The reversal of 256381638 is 836183652.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 256381638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256381633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4920 + ... + 23172.

It is an arithmetic number, because the mean of its divisors is an integer number (32063151).

Almost surely, 2^256381638 is an apocalyptic number.

256381638 is an abundant number, since it is smaller than the sum of its proper divisors (256628778).

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

256381638 is a wasteful number, since it uses less digits than its factorization.

256381638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20599.

The product of its digits is 207360, while the sum is 42.

The square root of 256381638 is about 16011.9217459991. The cubic root of 256381638 is about 635.2757915001.

The spelling of 256381638 in words is "two hundred fifty-six million, three hundred eighty-one thousand, six hundred thirty-eight".