638133636 has 96 divisors (see below), whose sum is σ = 1765048320. Its totient is φ = 175593600.

The previous prime is 638133611. The next prime is 638133647. The reversal of 638133636 is 636331836.

It is a junction number, because it is equal to n+sod(n) for n = 638133594 and 638133603.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 700021 + ... + 700931.

It is an arithmetic number, because the mean of its divisors is an integer number (18385920).

Almost surely, 2^638133636 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 638133636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (882524160).

638133636 is an abundant number, since it is smaller than the sum of its proper divisors (1126914684).

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

638133636 is a wasteful number, since it uses less digits than its factorization.

638133636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1225 (or 1223 counting only the distinct ones).

The product of its digits is 139968, while the sum is 39.

The square root of 638133636 is about 25261.3070920727. The cubic root of 638133636 is about 860.9353605288.

The spelling of 638133636 in words is "six hundred thirty-eight million, one hundred thirty-three thousand, six hundred thirty-six".