TITLE: Why are smooth numbers called "smooth"?
QUESTION [13 upvotes]: "Adleman refers to integers which factor completely into small primes as “smooth” numbers." (ME Hellman, JM Reyneri. Advances in Cryptology, 1983: citation link.)

Does anyone know what is the intuitive reason behind the choice of the adjective
"smooth" for this concept?

REPLY [4 votes]: As I far as I recall the story (as related to me by Len Adleman), Len had originally come up the notion of smooth numbers and needed an appropriate name for the definition. Ron suggested calling them 'smooth', and although Len rather disliked the term, he adopted it anyway.