Is my father eligible to apply to citizen? residency question

[cal2007]

My father has green card since Oct 20, 2002. He has been in and out of US as following -


PR since 10/20/2002

out of country Date from Date to days

11/30/2002 8/12/2003 255
6/20/2005 4/27/2006 311 (with permission)
7/25/2007 1/15/2008 174
6/25/2008 9/27/2008 94

834 (total days out)


Is he eligible to apply for US citizenship?

Thanks
Cal