Alexa is only part of the universe of stats gatherers, because they only track hits from people using their toolbars and other things and don't get the entire picture. You pretty much have to get the stats from the horse's mouth to know what they really are for a given website. The Indexing and lds.org stats came to me that way in various presentations.
In fact I've heard that usually most of the traffic spikes lds.org has are on Saturday nights, and this is noticeable even on the Alexa stats. Sunday morning sees a secondary spike, and on General Conference weekends there are a lot of people coming to the site to listen to or download Conference.
For Facebook stats, lds.org has over 300,000 fans, and there are pages for each of the magazines, the Youtube channel, and others. Some of them list the other pages on the left and you can see the number of fans each page has at the moment by visiting those pages.
Mormon Channel has 43,100 fans as of this moment. Among religious broadcasters that have a Facebook page, it is in third place for stations, and third place for owners. The top two stations as far as far as Facebook fan totals go right now are owned by the same party, and the reason it's third place for stations is one group owner owns a number of stations that each has their own Facebook pages. Many of the rest in that programming genre are either just getting started themselves. or there are other reasons why the fan base count is not as big as would otherwise be expected, and some of these are very widely known of in the broadcasting industry.