Douglas Adams chose 42 for Deep Thought's answer in the 1978 Hitchhiker's Guide radio series, and insisted it was an ordinary, unimportant number, that was the joke. Entirely separately, Jewish tradition guards a 42-letter name of God: the Ana Bekoach prayer encodes it acrostically, seven lines of six words, the first letter of each word spelling the name; Talmudic and Zoharic sources tie 42 to the name Ehyeh doubled, 21 plus 21, and to the 42 encampments of the exodus. No evidence connects the two traditions, and Adams denied any.
The story the Kabbalists tell: the 42-letter name was the seal the High Priest spoke in the Holy of Holies on Yom Kippur, the formula with which the world was made, and after the Temple fell the name was hidden, in Ana Bekoach, in the first 42 letters of Genesis, in the Ve'ahavta's 42 words, for anyone who knows how to count. The Zohar blames transcription errors for the name's apparent loss: it is not missing, it is misfiled.
The claim: Adams accidentally performed the oldest mystical operation, asking the ultimate question and receiving an answer that forces the questioner to find a better question. Deep Thought's whole point is that 42 is meaningless without knowing what was asked, which is precisely what the Kabbalists say about the name: the number is a container, and the work is discovering what it contains. Two traditions, one punchline.
The comedy writer picked a boring number on purpose, and the mystics had treasured it for centuries. Which one understood the joke better?