6639909 has 16 divisors (see below), whose sum is σ = 9320640. Its totient is φ = 4199040.

The previous prime is 6639907. The next prime is 6639929. The reversal of 6639909 is 9099366.

It is not a de Polignac number, because 6639909 - 2¹ = 6639907 is a prime.

6639909 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6639907) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3822 + ... + 5280.

It is an arithmetic number, because the mean of its divisors is an integer number (582540).

Almost surely, 2^6639909 is an apocalyptic number.

It is an amenable number.

6639909 is a deficient number, since it is larger than the sum of its proper divisors (2680731).

6639909 is a wasteful number, since it uses less digits than its factorization.

6639909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1540.

The product of its (nonzero) digits is 78732, while the sum is 42.

The square root of 6639909 is about 2576.8020878601. The cubic root of 6639909 is about 187.9550688611.

The spelling of 6639909 in words is "six million, six hundred thirty-nine thousand, nine hundred nine".