639947880 has 384 divisors, whose sum is σ = 2528547840. Its totient is φ = 138240000.

The previous prime is 639947879. The next prime is 639947899. The reversal of 639947880 is 88749936.

639947880 is a `hidden beast` number, since 6 + 3 + 99 + 478 + 80 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1595680 + ... + 1596080.

It is an arithmetic number, because the mean of its divisors is an integer number (6584760).

Almost surely, 2^639947880 is an apocalyptic number.

639947880 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 639947880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1264273920).

639947880 is an abundant number, since it is smaller than the sum of its proper divisors (1888599960).

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

639947880 is a wasteful number, since it uses less digits than its factorization.

639947880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 473 (or 466 counting only the distinct ones).

The product of its (nonzero) digits is 2612736, while the sum is 54.

The square root of 639947880 is about 25297.1911484259. The cubic root of 639947880 is about 861.7504818077.

The spelling of 639947880 in words is "six hundred thirty-nine million, nine hundred forty-seven thousand, eight hundred eighty".