639143820 has 216 divisors, whose sum is σ = 2269167264. Its totient is φ = 142636032.

The previous prime is 639143779. The next prime is 639143839. The reversal of 639143820 is 28341936.

639143820 is a `hidden beast` number, since 639 + 14 + 3 + 8 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 5656084 + ... + 5656196.

It is an arithmetic number, because the mean of its divisors is an integer number (10505404).

Almost surely, 2^639143820 is an apocalyptic number.

639143820 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639143820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1134583632).

639143820 is an abundant number, since it is smaller than the sum of its proper divisors (1630023444).

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

639143820 is a wasteful number, since it uses less digits than its factorization.

639143820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 639143820 is about 25281.2938751164. The cubic root of 639143820 is about 861.3894162097.

The spelling of 639143820 in words is "six hundred thirty-nine million, one hundred forty-three thousand, eight hundred twenty".