639434880 has 192 divisors, whose sum is σ = 2523643200. Its totient is φ = 146147328.

The previous prime is 639434863. The next prime is 639434909. The reversal of 639434880 is 88434936.

639434880 is a `hidden beast` number, since 639 + 4 + 3 + 4 + 8 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-2 number, since 2×639434880² = 817753931521228800, which contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32391 + ... + 48249.

It is an arithmetic number, because the mean of its divisors is an integer number (13143975).

Almost surely, 2^639434880 is an apocalyptic number.

639434880 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 639434880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1261821600).

639434880 is an abundant number, since it is smaller than the sum of its proper divisors (1884208320).

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

639434880 is a wasteful number, since it uses less digits than its factorization.

639434880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15891 (or 15876 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 45.

The square root of 639434880 is about 25287.0496499691. The cubic root of 639434880 is about 861.5201525413.

The spelling of 639434880 in words is "six hundred thirty-nine million, four hundred thirty-four thousand, eight hundred eighty".