Oh I get it now:

2^16-1 K = 65535 K = (65535 - 273.15)°C = 65261.8°C (Kelvin by far is the best temperature unit)

Also, -273.1°C sounds pretty scary too considering it's 0.05°C above absolute zero... (it's so cold that helium is liquid at this temperatue and also a superfluid!)