6639985 has 32 divisors (see below), whose sum is σ = 9434880. Its totient is φ = 4435200.

The previous prime is 6639943. The next prime is 6639989. The reversal of 6639985 is 5899366.

It is a de Polignac number, because none of the positive numbers 2^k-6639985 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6639989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 36595 + ... + 36775.

It is an arithmetic number, because the mean of its divisors is an integer number (294840).

Almost surely, 2^6639985 is an apocalyptic number.

It is an amenable number.

6639985 is a deficient number, since it is larger than the sum of its proper divisors (2794895).

6639985 is a wasteful number, since it uses less digits than its factorization.

6639985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249.

The product of its digits is 349920, while the sum is 46.

The square root of 6639985 is about 2576.8168347789. The cubic root of 6639985 is about 187.9557859659.

It can be divided in two parts, 663 and 9985, that added together give a cube (10648 = 22³).

The spelling of 6639985 in words is "six million, six hundred thirty-nine thousand, nine hundred eighty-five".