16

Sixteen (16) is a positive integer one more than 15 and one less than 17.

Properties
A base 16 system is called hexadecimal. The digits most commonly used to represent it are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F. A digit in hexadecimal corresponds to a string of four digits in binary. 16 is the fourth square number (between 9 and 25) and the second fourth power (between 1 and 81). It is the only number that is equal to both x^y and y^x where both are positive integers.

16 is the third power of two, between 8 and 32. Being the 4th power of two, which is itslef a power of two, it shows up frequently in computer science, such as the hexadecimal number system.