US Presidents Trivia: Who is the oldest living former President?

As of this moment, only four former Presidents are still living: George H.W. Bush, Jimmy Carter, Bill Clinton and George W. Bush.  It's a pretty small number, but that isn't too surprising: Presidents are usually relatively old when they retire.  The most recent former President to die was Gerald Ford, who died in 2006 at the age of 93 (incentially, this made Ford the longest living President).   So, off of Pocket Trivia: US Presidents - which of the above Presidents is the oldest still living?
The correct answer to this one is George H.W. Bush.  At 86, George H.W. Bush has lived longer than Jimmy Carter (86), Bill Clinton (64) or his son, George W. Bush (also 64).