6639855 has 16 divisors (see below), whose sum is σ = 10675680. Its totient is φ = 3523968.

The previous prime is 6639851. The next prime is 6639863. The reversal of 6639855 is 5589366.

It is not a de Polignac number, because 6639855 - 2² = 6639851 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6639851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2469 + ... + 4401.

It is an arithmetic number, because the mean of its divisors is an integer number (667230).

Almost surely, 2^6639855 is an apocalyptic number.

6639855 is a deficient number, since it is larger than the sum of its proper divisors (4035825).

6639855 is a wasteful number, since it uses less digits than its factorization.

6639855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2170.

The product of its digits is 194400, while the sum is 42.

The square root of 6639855 is about 2576.7916097349. The cubic root of 6639855 is about 187.9545593360.

The spelling of 6639855 in words is "six million, six hundred thirty-nine thousand, eight hundred fifty-five".