6686 has 4 divisors (see below), whose sum is σ = 10032. Its totient is φ = 3342.

The previous prime is 6679. The next prime is 6689. The reversal of 6686 is 6866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6866 = 2 ⋅3433.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1670 + ... + 1673.

It is an arithmetic number, because the mean of its divisors is an integer number (2508).

2⁶⁶⁸⁶ is an apocalyptic number.

6686 is a deficient number, since it is larger than the sum of its proper divisors (3346).

6686 is a wasteful number, since it uses less digits than its factorization.

6686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3345.

The product of its digits is 1728, while the sum is 26.

The square root of 6686 is about 81.7679643870. The cubic root of 6686 is about 18.8388963822.

The spelling of 6686 in words is "six thousand, six hundred eighty-six".