6643816 has 8 divisors (see below), whose sum is σ = 12457170. Its totient is φ = 3321904.

The previous prime is 6643811. The next prime is 6643823. The reversal of 6643816 is 6183466.

It can be written as a sum of positive squares in only one way, i.e., 5541316 + 1102500 = 2354^2 + 1050^2 .

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

It is not an unprimeable number, because it can be changed into a prime (6643811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 415231 + ... + 415246.

Almost surely, 2^6643816 is an apocalyptic number.

It is an amenable number.

6643816 is a deficient number, since it is larger than the sum of its proper divisors (5813354).

6643816 is a wasteful number, since it uses less digits than its factorization.

6643816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830483 (or 830479 counting only the distinct ones).

The product of its digits is 20736, while the sum is 34.

The square root of 6643816 is about 2577.5600865935. The cubic root of 6643816 is about 187.9919266187.

The spelling of 6643816 in words is "six million, six hundred forty-three thousand, eight hundred sixteen".