638180816 has 320 divisors, whose sum is σ = 1799884800. Its totient is φ = 211673088.

The previous prime is 638180783. The next prime is 638180821. The reversal of 638180816 is 618081836.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 10816595 + ... + 10816653.

It is an arithmetic number, because the mean of its divisors is an integer number (5624640).

Almost surely, 2^638180816 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 638180816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (899942400).

638180816 is an abundant number, since it is smaller than the sum of its proper divisors (1161703984).

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

638180816 is a wasteful number, since it uses less digits than its factorization.

638180816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 41.

The square root of 638180816 is about 25262.2409140599. The cubic root of 638180816 is about 860.9565775734.

The spelling of 638180816 in words is "six hundred thirty-eight million, one hundred eighty thousand, eight hundred sixteen".