6399985 has 4 divisors (see below), whose sum is σ = 7679988. Its totient is φ = 5119984.

The previous prime is 6399971. The next prime is 6400013. The reversal of 6399985 is 5899936.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3073009 + 3326976 = 1753^2 + 1824^2 .

It is a cyclic number.

It is not a de Polignac number, because 6399985 - 2²¹ = 4302833 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 639994 + ... + 640003.

It is an arithmetic number, because the mean of its divisors is an integer number (1919997).

Almost surely, 2^6399985 is an apocalyptic number.

It is an amenable number.

6399985 is a deficient number, since it is larger than the sum of its proper divisors (1280003).

6399985 is a wasteful number, since it uses less digits than its factorization.

6399985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280002.

The product of its digits is 524880, while the sum is 49.

The square root of 6399985 is about 2529.8191634977. The cubic root of 6399985 is about 185.6634082947.

Subtracting from 6399985 its sum of digits (49), we obtain a palindrome (6399936).

The spelling of 6399985 in words is "six million, three hundred ninety-nine thousand, nine hundred eighty-five".