639988992 has 144 divisors (see below), whose sum is σ = 1929372480. Its totient is φ = 209184768.

The previous prime is 639988981. The next prime is 639988997. The reversal of 639988992 is 299889936.

It is a tau number, because it is divible by the number of its divisors (144).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639988997) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 365463 + ... + 367209.

It is an arithmetic number, because the mean of its divisors is an integer number (13398420).

Almost surely, 2^639988992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639988992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (964686240).

639988992 is an abundant number, since it is smaller than the sum of its proper divisors (1289383488).

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

639988992 is a wasteful number, since it uses less digits than its factorization.

639988992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1825 (or 1805 counting only the distinct ones).

The product of its digits is 15116544, while the sum is 63.

The square root of 639988992 is about 25298.0037157085. The cubic root of 639988992 is about 861.7689351475.

The spelling of 639988992 in words is "six hundred thirty-nine million, nine hundred eighty-eight thousand, nine hundred ninety-two".