639432 has 48 divisors (see below), whose sum is σ = 1769040. Its totient is φ = 208608.

The previous prime is 639391. The next prime is 639433. The reversal of 639432 is 234936.

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

It is a junction number, because it is equal to n+sod(n) for n = 639396 and 639405.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639432.

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 11 ways as a sum of consecutive naturals, for example, 5923 + ... + 6029.

It is an arithmetic number, because the mean of its divisors is an integer number (36855).

2⁶³⁹⁴³² 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 639432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (884520).

639432 is an abundant number, since it is smaller than the sum of its proper divisors (1129608).

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

639432 is a wasteful number, since it uses less digits than its factorization.

639432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202 (or 195 counting only the distinct ones).

The product of its digits is 3888, while the sum is 27.

The square root of 639432 is about 799.6449211994. The cubic root of 639432 is about 86.1518859117.

Subtracting from 639432 its reverse (234936), we obtain a square (404496 = 636²).

The spelling of 639432 in words is "six hundred thirty-nine thousand, four hundred thirty-two".