6639591 has 16 divisors (see below), whose sum is σ = 10155008. Its totient is φ = 3780000.

The previous prime is 6639547. The next prime is 6639593. The reversal of 6639591 is 1959366.

It is not a de Polignac number, because 6639591 - 2⁶ = 6639527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6639593) 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, 8466 + ... + 9216.

It is an arithmetic number, because the mean of its divisors is an integer number (634688).

Almost surely, 2^6639591 is an apocalyptic number.

6639591 is a deficient number, since it is larger than the sum of its proper divisors (3515417).

6639591 is a wasteful number, since it uses less digits than its factorization.

6639591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1182.

The product of its digits is 43740, while the sum is 39.

The square root of 6639591 is about 2576.7403827316. The cubic root of 6639591 is about 187.9520682846.

The spelling of 6639591 in words is "six million, six hundred thirty-nine thousand, five hundred ninety-one".