There are many number base (radix) systems exist. Base 36 is not the largest
base number, it comes from the number of digits (0-9 = 10) and the number of
letters in alphabet (A-Z = 26). You may add more symbols and create new number
bases to count.
Base 10 (decimal) is used in arithmetic. Base 2 (binary), base 8 (octal), base
16 (hexadecimal) are generally used in computing. Other base numbers 3, 4, 5,
6, 7, 9, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
29, 30, 31, 32, 33, 34, 35, 36 are used for different purposes.