639205 has 12 divisors (see below), whose sum is σ = 892620. Its totient is φ = 438144.

The previous prime is 639181. The next prime is 639211. The reversal of 639205 is 502936.

It can be written as a sum of positive squares in 2 ways, for example, as 268324 + 370881 = 518^2 + 609^2 .

It is not a de Polignac number, because 639205 - 2¹¹ = 637157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 639205.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1060 + ... + 1549.

It is an arithmetic number, because the mean of its divisors is an integer number (74385).

2⁶³⁹²⁰⁵ is an apocalyptic number.

It is an amenable number.

639205 is a deficient number, since it is larger than the sum of its proper divisors (253415).

639205 is a wasteful number, since it uses less digits than its factorization.

639205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2628 (or 2621 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 25.

The square root of 639205 is about 799.5029706011. The cubic root of 639205 is about 86.1416899916.

It can be divided in two parts, 63920 and 5, that multiplied together give a triangular number (319600 = T₇₉₉).

The spelling of 639205 in words is "six hundred thirty-nine thousand, two hundred five".