6643220 has 12 divisors (see below), whose sum is σ = 13950804. Its totient is φ = 2657280.

The previous prime is 6643213. The next prime is 6643229. The reversal of 6643220 is 223466.

It can be written as a sum of positive squares in 2 ways, for example, as 1643524 + 4999696 = 1282^2 + 2236^2 .

It is a hoax number, since the sum of its digits (23) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6643229) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 166061 + ... + 166100.

It is an arithmetic number, because the mean of its divisors is an integer number (1162567).

Almost surely, 2^6643220 is an apocalyptic number.

It is an amenable number.

6643220 is an abundant number, since it is smaller than the sum of its proper divisors (7307584).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6643220 is a wasteful number, since it uses less digits than its factorization.

6643220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332170 (or 332168 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 6643220 is about 2577.4444707888. Note that the first 4 decimals coincide. The cubic root of 6643220 is about 187.9863050232.

Adding to 6643220 its reverse (223466), we get a palindrome (6866686).

The spelling of 6643220 in words is "six million, six hundred forty-three thousand, two hundred twenty".