638865680826 has 8 divisors (see below), whose sum is σ = 1277731361664. Its totient is φ = 212955226940.

The previous prime is 638865680731. The next prime is 638865680879. The reversal of 638865680826 is 628086568836.

It is a sphenic number, since it is the product of 3 distinct primes.

638865680826 is an admirable number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53238806730 + ... + 53238806741.

It is an arithmetic number, because the mean of its divisors is an integer number (159716420208).

Almost surely, 2^638865680826 is an apocalyptic number.

638865680826 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

638865680826 is a wasteful number, since it uses less digits than its factorization.

638865680826 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106477613476.

The product of its (nonzero) digits is 159252480, while the sum is 66.

The spelling of 638865680826 in words is "six hundred thirty-eight billion, eight hundred sixty-five million, six hundred eighty thousand, eight hundred twenty-six".