An end-of-centure leap year always starts on a Saturday (as it did in 2000) so January 1, 4000 will also be a Saturday.
what day of the week was January 1st 1936
It was a Sunday :)
1st January 1960 was a Friday.
January 1st, 0001 fell on a Tuesday.
Friday
It can be on any day [Saturday, January 1, 2011]
1st of January 2010 is a Friday.
Wednesday
Wednesday
Monday
Wednesday
It was on a Sunday. :)