639749880 has 512 divisors, whose sum is σ = 2730240000. Its totient is φ = 132088320.

The previous prime is 639749879. The next prime is 639749911. The reversal of 639749880 is 88947936.

639749880 is a `hidden beast` number, since 63 + 97 + 498 + 8 + 0 = 666.

639749880 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 (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 4074762 + ... + 4074918.

It is an arithmetic number, because the mean of its divisors is an integer number (5332500).

Almost surely, 2^639749880 is an apocalyptic number.

639749880 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 639749880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1365120000).

639749880 is an abundant number, since it is smaller than the sum of its proper divisors (2090490120).

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

639749880 is a wasteful number, since it uses less digits than its factorization.

639749880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209 (or 185 counting only the distinct ones).

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

The square root of 639749880 is about 25293.2773677118. The cubic root of 639749880 is about 861.6615973839.

The spelling of 639749880 in words is "six hundred thirty-nine million, seven hundred forty-nine thousand, eight hundred eighty".