Have a look at Numbers API. It has some very interesting facts about numbers and even dates. For each request of the form
http://numbersapi.com/49 it returns a random trivia that refers to that number:
49 is the number of days and night Siddhartha Gautama spent meditating as a holy man.
And, of course:
42 is the result given by the web search engines Google, Wolfram Alpha and Bing when the query "the answer to life the universe and everything" is entered as a search.
/math to the number, the specific statements referring to the day of the year (e.g. 4th of July) or the year (e.g. 1492) can be returned.