6399665 has 8 divisors (see below), whose sum is σ = 7709568. Its totient is φ = 5099760.

The previous prime is 6399643. The next prime is 6399677. The reversal of 6399665 is 5669936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-6399665 is a prime.

It is a super-2 number, since 2×6399665² = 81911424224450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1007 + ... + 3716.

It is an arithmetic number, because the mean of its divisors is an integer number (963696).

Almost surely, 2^6399665 is an apocalyptic number.

It is an amenable number.

6399665 is a deficient number, since it is larger than the sum of its proper divisors (1309903).

6399665 is a wasteful number, since it uses less digits than its factorization.

6399665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4999.

The product of its digits is 262440, while the sum is 44.

The square root of 6399665 is about 2529.7559170797. The cubic root of 6399665 is about 185.6603138458.

The spelling of 6399665 in words is "six million, three hundred ninety-nine thousand, six hundred sixty-five".