638809884 has 72 divisors (see below), whose sum is σ = 1756027728. Its totient is φ = 194987520.

The previous prime is 638809859. The next prime is 638809891. The reversal of 638809884 is 488908836.

638809884 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 638809884.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8539 + ... + 36749.

It is an arithmetic number, because the mean of its divisors is an integer number (24389274).

Almost surely, 2^638809884 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638809884, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (878013864).

638809884 is an abundant number, since it is smaller than the sum of its proper divisors (1117217844).

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

638809884 is a wasteful number, since it uses less digits than its factorization.

638809884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28275 (or 28270 counting only the distinct ones).

The product of its (nonzero) digits is 2654208, while the sum is 54.

The square root of 638809884 is about 25274.6886034230. The cubic root of 638809884 is about 861.2393722300.

The spelling of 638809884 in words is "six hundred thirty-eight million, eight hundred nine thousand, eight hundred eighty-four".