28081831638 has 64 divisors (see below), whose sum is σ = 66484800000. Its totient is φ = 7736865024.

The previous prime is 28081831627. The next prime is 28081831703. The reversal of 28081831638 is 83613818082.

It is a congruent number.

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, 971113 + ... + 999611.

It is an arithmetic number, because the mean of its divisors is an integer number (1038825000).

Almost surely, 2^28081831638 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28081831638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33242400000).

28081831638 is an abundant number, since it is smaller than the sum of its proper divisors (38402968362).

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

28081831638 is a wasteful number, since it uses less digits than its factorization.

28081831638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29349.

The product of its (nonzero) digits is 442368, while the sum is 48.

The spelling of 28081831638 in words is "twenty-eight billion, eighty-one million, eight hundred thirty-one thousand, six hundred thirty-eight".