639085 has 4 divisors (see below), whose sum is σ = 766908. Its totient is φ = 511264.

The previous prime is 639083. The next prime is 639091. The reversal of 639085 is 580936.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 161604 + 477481 = 402^2 + 691^2 .

It is a cyclic number.

It is not a de Polignac number, because 639085 - 2¹ = 639083 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63904 + ... + 63913.

It is an arithmetic number, because the mean of its divisors is an integer number (191727).

2⁶³⁹⁰⁸⁵ is an apocalyptic number.

It is an amenable number.

639085 is a deficient number, since it is larger than the sum of its proper divisors (127823).

639085 is a wasteful number, since it uses less digits than its factorization.

639085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127822.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 639085 is about 799.4279204531. The cubic root of 639085 is about 86.1362991025.

The spelling of 639085 in words is "six hundred thirty-nine thousand, eighty-five".