How to check last reboot date and time in linux

we can check the last reboot date and time in linux servers by using the following commands

server # who -b
         system boot  2015-01-08 14:36

server # last reboot
reboot   system boot  2.6.18-448.16.1. Thu Jan  8 14:36         (53+11:08)

wtmp begins Tue Dec 30 06:27:45 2014