Sixty-eight is four times seventeen and reduces to fourteen and then five. In Jewish gematria it is the value of chaim, life, the plural form of chai used in the toast le-chaim, to life, and in the many names built on it, spelled chet, yod, yod, mem, totalling eight, ten, ten and forty. So where eighteen is chai, singular life, sixty-eight is chaim, life in its fuller plural, and the number carries a positive charge in Jewish usage, though it is far less commonly invoked than the eighteen of chai.
In chemistry, sixty-eight is the atomic number of erbium, the fourth element named for Ytterby, alongside yttrium, ytterbium and terbium, a single Swedish quarry village that lent its name to more elements than any other place on Earth.
Sixty-eight factors as 2^2 x 17 and carries 6 divisors in all. Summing its proper divisors gives only 58, short of the number itself, which places it among the deficient numbers in the same classical scheme.
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.