$ perl -wE'say log(~0)/log(2)'
64
$ perl -v

This is perl 5, version 16, subversion 0 (v5.16.0) built for i686-linux-64int-ld
$ ux
Linux 3.4.6-2.10-desktop [openSUSE 12.2 (Mantis)]  i386 Core(TM) i7-2620M CPU @ 2.70GHz/800(4) i686