6643520 has 56 divisors (see below), whose sum is σ = 17047464. Its totient is φ = 2451456.

The previous prime is 6643513. The next prime is 6643537. The reversal of 6643520 is 253466.

It can be written as a sum of positive squares in 4 ways, for example, as 7744 + 6635776 = 88^2 + 2576^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 6643520.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 3362 + ... + 4958.

It is an arithmetic number, because the mean of its divisors is an integer number (304419).

Almost surely, 2^6643520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6643520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8523732).

6643520 is an abundant number, since it is smaller than the sum of its proper divisors (10403944).

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

6643520 is a wasteful number, since it uses less digits than its factorization.

6643520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1627 (or 1617 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 26.

The square root of 6643520 is about 2577.5026673119. The cubic root of 6643520 is about 187.9891347274.

Adding to 6643520 its reverse (253466), we get a palindrome (6896986).

The spelling of 6643520 in words is "six million, six hundred forty-three thousand, five hundred twenty".