639880920 has 192 divisors, whose sum is σ = 2453667840. Its totient is φ = 141523200.

The previous prime is 639880877. The next prime is 639880949. The reversal of 639880920 is 29088936.

639880920 is a `hidden beast` number, since 639 + 8 + 8 + 0 + 9 + 2 + 0 = 666.

639880920 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 74025 + ... + 82215.

It is an arithmetic number, because the mean of its divisors is an integer number (12779520).

Almost surely, 2^639880920 is an apocalyptic number.

639880920 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 639880920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1226833920).

639880920 is an abundant number, since it is smaller than the sum of its proper divisors (1813786920).

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

639880920 is a wasteful number, since it uses less digits than its factorization.

639880920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8246 (or 8239 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The square root of 639880920 is about 25295.8676467126. The cubic root of 639880920 is about 861.7204247636.

The spelling of 639880920 in words is "six hundred thirty-nine million, eight hundred eighty thousand, nine hundred twenty".