639669960 has 160 divisors (see below), whose sum is σ = 2263377600. Its totient is φ = 161585280.

The previous prime is 639669929. The next prime is 639669983. The reversal of 639669960 is 69966936.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 639669897 and 639669906.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 56365 + ... + 66755.

It is an arithmetic number, because the mean of its divisors is an integer number (14146110).

Almost surely, 2^639669960 is an apocalyptic number.

639669960 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 639669960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1131688800).

639669960 is an abundant number, since it is smaller than the sum of its proper divisors (1623707640).

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

639669960 is a wasteful number, since it uses less digits than its factorization.

639669960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10433 (or 10420 counting only the distinct ones).

The product of its (nonzero) digits is 2834352, while the sum is 54.

The square root of 639669960 is about 25291.6974519307. The cubic root of 639669960 is about 861.6257152030.

The spelling of 639669960 in words is "six hundred thirty-nine million, six hundred sixty-nine thousand, nine hundred sixty".