6639809 has 8 divisors (see below), whose sum is σ = 7669728. Its totient is φ = 5680960.

The previous prime is 6639803. The next prime is 6639817. The reversal of 6639809 is 9089366.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6639809 - 2¹⁶ = 6574273 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6639803) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17567 + ... + 17940.

It is an arithmetic number, because the mean of its divisors is an integer number (958716).

Almost surely, 2^6639809 is an apocalyptic number.

It is an amenable number.

6639809 is a deficient number, since it is larger than the sum of its proper divisors (1029919).

6639809 is a wasteful number, since it uses less digits than its factorization.

6639809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35535.

The product of its (nonzero) digits is 69984, while the sum is 41.

The square root of 6639809 is about 2576.7826838909. The cubic root of 6639809 is about 187.9541252939.

The spelling of 6639809 in words is "six million, six hundred thirty-nine thousand, eight hundred nine".