639860 has 48 divisors (see below), whose sum is σ = 1524096. Its totient is φ = 223872.

The previous prime is 639857. The next prime is 639907. The reversal of 639860 is 68936.

It is a happy number.

639860 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5927 + ... + 6033.

It is an arithmetic number, because the mean of its divisors is an integer number (31752).

2⁶³⁹⁸⁶⁰ 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 639860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (762048).

639860 is an abundant number, since it is smaller than the sum of its proper divisors (884236).

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

639860 is a wasteful number, since it uses less digits than its factorization.

639860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152 (or 150 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 639860 is about 799.9124952143. The cubic root of 639860 is about 86.1711033752.

The spelling of 639860 in words is "six hundred thirty-nine thousand, eight hundred sixty".