638421888 has 256 divisors, whose sum is σ = 1974067200. Its totient is φ = 181149696.

The previous prime is 638421887. The next prime is 638421911. The reversal of 638421888 is 888124836.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638421887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5026881 + ... + 5027007.

It is an arithmetic number, because the mean of its divisors is an integer number (7711200).

Almost surely, 2^638421888 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 638421888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (987033600).

638421888 is an abundant number, since it is smaller than the sum of its proper divisors (1335645312).

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

638421888 is a wasteful number, since it uses less digits than its factorization.

638421888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229 (or 217 counting only the distinct ones).

The product of its digits is 589824, while the sum is 48.

The square root of 638421888 is about 25267.0118534028. The cubic root of 638421888 is about 861.0649723470.

The spelling of 638421888 in words is "six hundred thirty-eight million, four hundred twenty-one thousand, eight hundred eighty-eight".