6643988 has 24 divisors (see below), whose sum is σ = 12714912. Its totient is φ = 3019104.

The previous prime is 6643981. The next prime is 6643993. The reversal of 6643988 is 8893466.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6643981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2531 + ... + 4437.

It is an arithmetic number, because the mean of its divisors is an integer number (529788).

Almost surely, 2^6643988 is an apocalyptic number.

It is an amenable number.

6643988 is a deficient number, since it is larger than the sum of its proper divisors (6070924).

6643988 is a wasteful number, since it uses less digits than its factorization.

6643988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1991 (or 1989 counting only the distinct ones).

The product of its digits is 248832, while the sum is 44.

The square root of 6643988 is about 2577.5934512642. The cubic root of 6643988 is about 187.9935488959.

The spelling of 6643988 in words is "six million, six hundred forty-three thousand, nine hundred eighty-eight".