639825 has 24 divisors (see below), whose sum is σ = 1116000. Its totient is φ = 322560.

The previous prime is 639757. The next prime is 639833. The reversal of 639825 is 528936.

It is a happy number.

It is not a de Polignac number, because 639825 - 2⁷ = 639697 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639825.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1201 + ... + 1649.

It is an arithmetic number, because the mean of its divisors is an integer number (46500).

2⁶³⁹⁸²⁵ is an apocalyptic number.

It is an amenable number.

639825 is a deficient number, since it is larger than the sum of its proper divisors (476175).

639825 is a wasteful number, since it uses less digits than its factorization.

639825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481 (or 476 counting only the distinct ones).

The product of its digits is 12960, while the sum is 33.

The square root of 639825 is about 799.8906175222. The cubic root of 639825 is about 86.1695321754.

Subtracting from 639825 its reverse (528936), we obtain a square (110889 = 333²).

The spelling of 639825 in words is "six hundred thirty-nine thousand, eight hundred twenty-five".