Monday.
I'm assuming the questioner wanted to know what day of the week it was. In Unix/Linux/BSD/Cygwin one can use the "cal" program, like this:
cal 4 1961
28th day of April in 1961 was a Friday.
April 20, 1961 fell on a Thursday.
April 23, 1961 fell on a Sunday.
April 8, 1961 fell on a Saturday.
12 April 1961 was a Wednesday.
22 April 1961 was a Saturday.
30th April 1961 was a Sunday.
April 28 1961 was a Friday.
April 12th, 1961 fell on a Wednesday.
11 April 1961 was a Tuesday.
April 25, 1961 fell on a Tuesday.
April 23, 1961 fell on a Sunday.