638121792 has 224 divisors, whose sum is σ = 2229672960. Its totient is φ = 155934720.

The previous prime is 638121733. The next prime is 638121797. The reversal of 638121792 is 297121836.

It is a tau number, because it is divible by the number of its divisors (224).

It is a self number, because there is not a number n which added to its sum of digits gives 638121792.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638121797) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 250059 + ... + 252597.

Almost surely, 2^638121792 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 638121792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1114836480).

638121792 is an abundant number, since it is smaller than the sum of its proper divisors (1591551168).

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

638121792 is a wasteful number, since it uses less digits than its factorization.

638121792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2589 (or 2579 counting only the distinct ones).

The product of its digits is 36288, while the sum is 39.

The square root of 638121792 is about 25261.0726613103. The cubic root of 638121792 is about 860.9300340680.

The spelling of 638121792 in words is "six hundred thirty-eight million, one hundred twenty-one thousand, seven hundred ninety-two".