21696 is nontrivially palindromic in base 15.
It is an alternating number because its digits alternate between even and odd.
21696 is a nontrivial repdigit in base 15.
It is a plaindrome in base 15.
It is a nialpdrome in base 15.
It is a zygodrome in base 15.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21696.
It is an unprimeable number.
221696 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 21696, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28956).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21696 is a wasteful number, since it uses less digits than its factorization.
21696 is an odious number, because the sum of its binary digits is odd.
The square root of 21696 is about 147.2956211162. The cubic root of 21696 is about 27.8907305958.
The spelling of 21696 in words is "twenty-one thousand, six hundred ninety-six".