639806 has 16 divisors (see below), whose sum is σ = 1026000. Its totient is φ = 298368.

The previous prime is 639757. The next prime is 639833. The reversal of 639806 is 608936.

It is a happy number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639806.

It is an unprimeable number.

639806 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 7 ways as a sum of consecutive naturals, for example, 4220 + ... + 4368.

It is an arithmetic number, because the mean of its divisors is an integer number (64125).

2⁶³⁹⁸⁰⁶ is an apocalyptic number.

639806 is a deficient number, since it is larger than the sum of its proper divisors (386194).

639806 is a wasteful number, since it uses less digits than its factorization.

639806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283.

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

The square root of 639806 is about 799.8787408101. The cubic root of 639806 is about 86.1686792144.

The spelling of 639806 in words is "six hundred thirty-nine thousand, eight hundred six".