639438 has 16 divisors (see below), whose sum is σ = 1354320. Its totient is φ = 200576.

The previous prime is 639433. The next prime is 639439. The reversal of 639438 is 834936.

639438 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 639399 and 639408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639433) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3033 + ... + 3236.

It is an arithmetic number, because the mean of its divisors is an integer number (84645).

2⁶³⁹⁴³⁸ is an apocalyptic number.

639438 is an abundant number, since it is smaller than the sum of its proper divisors (714882).

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

639438 is a wasteful number, since it uses less digits than its factorization.

639438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6291.

The product of its digits is 15552, while the sum is 33.

The square root of 639438 is about 799.6486728558. The cubic root of 639438 is about 86.1521553747.

The spelling of 639438 in words is "six hundred thirty-nine thousand, four hundred thirty-eight".