Adding to 21296 its sum of digits (20), we get a square (21316 = 1462).
Adding to 21296 its product of digits (216), we get a palindrome (21512).
It is an alternating number because its digits alternate between even and odd.
It is a nialpdrome in base 16.
It is an unprimeable number.
21296 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
221296 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 21296, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22692).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21296 is an equidigital number, since it uses as much as digits as its factorization.
21296 is an evil number, because the sum of its binary digits is even.
The square root of 21296 is about 145.9314907756. The cubic root of 21296 is about 27.7182630977.
The spelling of 21296 in words is "twenty-one thousand, two hundred ninety-six".