6643021 has 32 divisors (see below), whose sum is σ = 8994816. Its totient is φ = 4791600.

The previous prime is 6643019. The next prime is 6643033. The reversal of 6643021 is 1203466.

It is not a de Polignac number, because 6643021 - 2¹ = 6643019 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6642983 and 6643001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6643051) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 214276 + ... + 214306.

It is an arithmetic number, because the mean of its divisors is an integer number (281088).

Almost surely, 2^6643021 is an apocalyptic number.

It is an amenable number.

6643021 is a deficient number, since it is larger than the sum of its proper divisors (2351795).

6643021 is a wasteful number, since it uses less digits than its factorization.

6643021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94 (or 72 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 6643021 is about 2577.4058663703. The cubic root of 6643021 is about 187.9844279391.

Adding to 6643021 its reverse (1203466), we get a palindrome (7846487).

The spelling of 6643021 in words is "six million, six hundred forty-three thousand, twenty-one".