1686 is nontrivially palindromic in base 13 and base 16.
It is a sphenic number, since it is the product of 3 distinct primes.
1686 is an admirable number.
1686 is an undulating number in base 13 and base 16.
It is a Curzon number.
It is a nialpdrome in base 12, base 14 and base 15.
It is a congruent number.
It is an unprimeable number.
1686 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1686 is a wasteful number, since it uses less digits than its factorization.
1686 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 286.
The square root of 1686 is about 41.0609303353. The cubic root of 1686 is about 11.9019792861.
The spelling of 1686 in words is "one thousand, six hundred eighty-six".