21696 has 28 divisors (see below), whose sum is σ = 57912. Its totient is φ = 7168.

The previous prime is 21683. The next prime is 21701. The reversal of 21696 is 69612.

21696 is nontrivially palindromic in base 15.

It is a Harshad number since it is a multiple of its sum of digits (24).

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.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 136 + ... + 248.

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).

21696 is an abundant number, since it is smaller than the sum of its proper divisors (36216).

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 sum of its prime factors is 128 (or 118 counting only the distinct ones).

The product of its digits is 648, while the sum is 24.

The square root of 21696 is about 147.2956211162. The cubic root of 21696 is about 27.8907305958.

It can be divided in two parts, 216 and 96, that multiplied together give a 4-th power (20736 = 12⁴).

The spelling of 21696 in words is "twenty-one thousand, six hundred ninety-six".