638816768 has 30 divisors (see below), whose sum is σ = 1277529561. Its totient is φ = 319122432.

The previous prime is 638816767. The next prime is 638816779. The reversal of 638816768 is 867618836.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 450797824 + 188018944 = 21232^2 + 13712^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=17872.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638816767) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 571346 + ... + 572462.

Almost surely, 2^638816768 is an apocalyptic number.

It is an amenable number.

638816768 is a deficient number, since it is larger than the sum of its proper divisors (638712793).

638816768 is an frugal number, since it uses more digits than its factorization.

638816768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2252 (or 1119 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 53.

The square root of 638816768 is about 25274.8247867320. The cubic root of 638816768 is about 861.2424658737.

The spelling of 638816768 in words is "six hundred thirty-eight million, eight hundred sixteen thousand, seven hundred sixty-eight".