Subtracting from 21323 its sum of digits (11), we obtain a palindrome (21312).
Adding to 21323 its reverse (32312), we get a palindrome (53635).
It is a weak prime.
It is a cyclic number.
It is an Ulam number.
It is a d-powerful number, because it can be written as 23 + 1 + 38 + 213 + 38 .
It is a nialpdrome in base 9.
221323 is an apocalyptic number.
21323 is an equidigital number, since it uses as much as digits as its factorization.
21323 is an evil number, because the sum of its binary digits is even.
The square root of 21323 is about 146.0239706350. The cubic root of 21323 is about 27.7299722926.
The spelling of 21323 in words is "twenty-one thousand, three hundred twenty-three", and thus it is an iban number.