6647 has 6 divisors (see below), whose sum is σ = 7368. Its totient is φ = 5984.

The previous prime is 6637. The next prime is 6653. The reversal of 6647 is 7466.

It is not a de Polignac number, because 6647 - 2¹⁰ = 5623 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 6647.

It is not an unprimeable number, because it can be changed into a prime (6607) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 278 + ... + 300.

It is an arithmetic number, because the mean of its divisors is an integer number (1228).

2⁶⁶⁴⁷ is an apocalyptic number.

6647 is a deficient number, since it is larger than the sum of its proper divisors (721).

6647 is a wasteful number, since it uses less digits than its factorization.

6647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57 (or 40 counting only the distinct ones).

The product of its digits is 1008, while the sum is 23.

The square root of 6647 is about 81.5291358963. The cubic root of 6647 is about 18.8021953072.

Adding to 6647 its sum of digits (23), we get a triangular number (6670 = T₁₁₅).

Multiplying 6647 by its sum of digits (23), we get a square (152881 = 391²).

6647 divided by its sum of digits (23) gives a square (289 = 17²).

The spelling of 6647 in words is "six thousand, six hundred forty-seven".