Sixty-five is five times thirteen and reduces to eleven and then two. In Jewish gematria it is the value of Adonai, my Lord, the word spoken in place of the unpronounced Tetragrammaton, aleph, dalet, nun, yod, totalling one, four, fifty and ten. So sixty-five stands for the spoken name of God as twenty-six stands for the written one, and the two are often paired in Kabbalistic reflection, their sum of ninety-one uniting the written and the pronounced Name. The number thus carries genuine weight in the arithmetic of the divine names.
In chemistry, sixty-five is the atomic number of terbium, one of four elements named after Ytterby, a single village and quarry in Sweden that also gave its name to yttrium, ytterbium and erbium, a concentration of naming unmatched anywhere else on the periodic table. Carl Gustaf Mosander isolated it in 1843.
The whole apparatus of digit-reduction numerology is a twentieth-century invention rather than an inheritance from antiquity. Mrs. L. Dow Balliett published the first systematic version, The Philosophy of Numbers, in 1908, fixing the letter-to-number chart still used today and ruling that eleven and twenty-two must stand as master numbers rather than reduce further; her colleague, the physician Julia Seton, is credited with coining the word numerology itself around 1912.