639812 has 18 divisors (see below), whose sum is σ = 1197882. Its totient is φ = 297984.

The previous prime is 639757. The next prime is 639833. The reversal of 639812 is 218936.

It can be written as a sum of positive squares in 3 ways, for example, as 141376 + 498436 = 376^2 + 706^2 .

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639812.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6548 + ... + 6644.

It is an arithmetic number, because the mean of its divisors is an integer number (66549).

2⁶³⁹⁸¹² is an apocalyptic number.

It is an amenable number.

639812 is a deficient number, since it is larger than the sum of its proper divisors (558070).

639812 is a wasteful number, since it uses less digits than its factorization.

639812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215 (or 116 counting only the distinct ones).

The product of its digits is 2592, while the sum is 29.

The square root of 639812 is about 799.8824913698. The cubic root of 639812 is about 86.1689485724.

The spelling of 639812 in words is "six hundred thirty-nine thousand, eight hundred twelve".