Sixty-seven is prime and reduces to thirteen and then four. Its principal traditional weight is gematria: the Hebrew word binah, understanding, is spelled bet, yod, nun, he, two, ten, fifty and five, totalling sixty-seven, and Binah is the name of the third sefirah on the Kabbalistic Tree of Life, the supernal mother, the faculty of contemplative understanding through which the flash of wisdom is given form. So sixty-seven carries the weight of one of the great emanations in Jewish mysticism.
In chemistry, sixty-seven is the atomic number of holmium, named after Holmia, the Latin name for Stockholm, and discovered in 1878.
Sixty-seven is prime, with no factors beyond one and itself. It has none of the more decorated properties, twin primeness, expressibility as a sum of two squares, that recreational number theory prizes in some of its neighbours, which makes it a plain prime rather than a celebrated one.
A separate and older-claimed system, generally called Chaldean numerology, assigns letters to digits irregularly rather than in Balliett's repeating one-to-nine sequence, and deliberately omits nine from the chart as too sacred to attach to an ordinary letter; its popular billing as a genuinely ancient Babylonian system rests on assertion rather than on any textual evidence that has been traced back that far.