638794818 has 12 divisors (see below), whose sum is σ = 1384055478. Its totient is φ = 212931600.

The previous prime is 638794811. The next prime is 638794837. The reversal of 638794818 is 818497836.

It can be written as a sum of positive squares in only one way, i.e., 437353569 + 201441249 = 20913^2 + 14193^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (638794811) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17744283 + ... + 17744318.

Almost surely, 2^638794818 is an apocalyptic number.

638794818 is an abundant number, since it is smaller than the sum of its proper divisors (745260660).

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

638794818 is a wasteful number, since it uses less digits than its factorization.

638794818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35488609 (or 35488606 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 54.

The square root of 638794818 is about 25274.3905564506. The cubic root of 638794818 is about 861.2326015487.

The spelling of 638794818 in words is "six hundred thirty-eight million, seven hundred ninety-four thousand, eight hundred eighteen".