6643 has 8 divisors (see below), whose sum is σ = 8288. Its totient is φ = 5184.

The previous prime is 6637. The next prime is 6653. The reversal of 6643 is 3466.

It is a happy number.

6643 is nontrivially palindromic in base 2, base 3 and base 9.

6643 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 6-Lehmer number, since φ(6643) divides (6643-1)⁶.

It is a cyclic number.

It is not a de Polignac number, because 6643 - 2⁹ = 6131 is a prime.

It is the 82-nd Hogben number.

6643 is an undulating number in base 9.

It is a nialpdrome in base 10.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 6643.

It is not an unprimeable number, because it can be changed into a prime (6653) by changing a digit.

It is a nontrivial repunit in base 81.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55 + ... + 127.

It is an arithmetic number, because the mean of its divisors is an integer number (1036).

2⁶⁶⁴³ is an apocalyptic number.

6643 is a deficient number, since it is larger than the sum of its proper divisors (1645).

6643 is a wasteful number, since it uses less digits than its factorization.

6643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93.

The product of its digits is 432, while the sum is 19.

The square root of 6643 is about 81.5046010971. The cubic root of 6643 is about 18.7984229853.

The spelling of 6643 in words is "six thousand, six hundred forty-three".