Who knows fifty-two?
Please cite/link your sources, if possible. At some point in the next few days, I will:
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52 is the numerical value of one of the possible expansions of Hashem's Four-Lettered Name (known as מילוי ההי"ן, because the two letters ה are each expanded to ה"ה). It is known as שם ב"ן, and is associated with the lower (spiritual and physical) worlds.
As an example of this, R' Shneur Zalman of Liadi observes (Shaar Hayichud Veha'emunah, end of ch. 7) that a stone, called in Hebrew אבן, ultimately derives its very limited life-force (through a tremendous number of condensations (tzimtzumim) of Divine energy) from this Name, "with an additional letter א from some other [Divine] Name, for a reason known to its Creator."
Moed Katan 28a says that Shmuel lived for fifty two years. Sifri - on the last page - line 9 lists six pairs that had the same lifespan. One of them is Shmuel and Shlomo. Thus Shlomo HaMelech also lived for fifty two years.
See also Aish.com regarding the age of Shlomo HaMelech when he died.