638638108758 has 192 divisors, whose sum is σ = 1623448008000. Its totient is φ = 179635691520.

The previous prime is 638638108697. The next prime is 638638108769. The reversal of 638638108758 is 857801836836.

It is a junction number, because it is equal to n+sod(n) for n = 638638108695 and 638638108704.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 37340893 + ... + 37357991.

It is an arithmetic number, because the mean of its divisors is an integer number (8455458375).

Almost surely, 2^638638108758 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638638108758, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (811724004000).

638638108758 is an abundant number, since it is smaller than the sum of its proper divisors (984809899242).

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

638638108758 is a wasteful number, since it uses less digits than its factorization.

638638108758 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17407 (or 17404 counting only the distinct ones).

The product of its (nonzero) digits is 46448640, while the sum is 63.

The spelling of 638638108758 in words is "six hundred thirty-eight billion, six hundred thirty-eight million, one hundred eight thousand, seven hundred fifty-eight".