65536

65536 is the number after 65535 and before 65537.

It is a power of two (2^16), four (4^8), 16 (16^4), and 256 (256^2).

65536 is also the smallest number that cannot be expressed with the unsigned short type in C++ (32768 is the smallest positive number that cannot be expressed with the regular short type).

In Ultrex function terms,65536 is the solution to 2 u 2 and therefore the third exponent in 2 u 3 and the bound of 2 uu 2 (which is 2 u (2 u 2) or 2 u 65536). It is the only solution to an integer ultrexed to a bound greater than 1 that has less than 3,600,000,000,000 digits.