Main Page | See live article | Alphabetical index For the year A.D. 51, see 51. Fifty-one (51, LI) is the natural number following fifty and preceeding fifty-two. Its divisors are 1, 3, 17, and 51; its factorisation is Fifty-one is also: The atomic number of antimony. The code for international direct dial phone calls to Peru. Part of the title of a collection of stories by Lord Dunsany, Fifty-One Tales. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.