The number 65,536 is an awkward figure to everyone except a hacker, who recognizes it more readily than his own mother's date of birth: It happens to be a power of 2--216 power to be exact--and even the exponent 16 is equal to 24, and 4 is equal to 22. Along with 256; 32,768; and 2,147,483,648; 65,536 is one of the foundation stones of the hacker universe, in which 2 is the only really important number because that's how many digits a computer can recognize.