639844128 has 432 divisors, whose sum is σ = 2377222848. Its totient is φ = 159667200.

The previous prime is 639844063. The next prime is 639844141. The reversal of 639844128 is 821448936.

It is a happy number.

639844128 is a `hidden beast` number, since 639 + 8 + 4 + 4 + 1 + 2 + 8 = 666.

It is a super-3 number, since 3×639844128³ (a number of 27 digits) contains 333 as substring.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 10489218 + ... + 10489278.

Almost surely, 2^639844128 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 639844128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1188611424).

639844128 is an abundant number, since it is smaller than the sum of its proper divisors (1737378720).

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

639844128 is a wasteful number, since it uses less digits than its factorization.

639844128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149 (or 127 counting only the distinct ones).

The product of its digits is 331776, while the sum is 45.

The square root of 639844128 is about 25295.1404028521. The cubic root of 639844128 is about 861.7039086564.

The spelling of 639844128 in words is "six hundred thirty-nine million, eight hundred forty-four thousand, one hundred twenty-eight".