6643864 has 8 divisors (see below), whose sum is σ = 12457260. Its totient is φ = 3321928.

The previous prime is 6643859. The next prime is 6643883. The reversal of 6643864 is 4683466.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 415234 + ... + 415249.

Almost surely, 2^6643864 is an apocalyptic number.

It is an amenable number.

6643864 is a deficient number, since it is larger than the sum of its proper divisors (5813396).

6643864 is a wasteful number, since it uses less digits than its factorization.

6643864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830489 (or 830485 counting only the distinct ones).

The product of its digits is 82944, while the sum is 37.

The square root of 6643864 is about 2577.5693977078. The cubic root of 6643864 is about 187.9923793501.

The spelling of 6643864 in words is "six million, six hundred forty-three thousand, eight hundred sixty-four".