639924 has 12 divisors (see below), whose sum is σ = 1493184. Its totient is φ = 213304.

The previous prime is 639911. The next prime is 639937. The reversal of 639924 is 429936.

639924 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (639911) and next prime (639937).

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26652 + ... + 26675.

It is an arithmetic number, because the mean of its divisors is an integer number (124432).

2⁶³⁹⁹²⁴ is an apocalyptic number.

It is an amenable number.

639924 is an abundant number, since it is smaller than the sum of its proper divisors (853260).

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

639924 is a wasteful number, since it uses less digits than its factorization.

639924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53334 (or 53332 counting only the distinct ones).

The product of its digits is 11664, while the sum is 33.

The square root of 639924 is about 799.9524985898. The cubic root of 639924 is about 86.1739762780.

The spelling of 639924 in words is "six hundred thirty-nine thousand, nine hundred twenty-four".