In Italian superstition, seventeen is traditionally considered unlucky.
The association is often linked to the Roman numeral XVII. When its letters are rearranged as VIXI, they resemble a Latin expression meaning “I have lived,” a phrase associated with death. This wordplay helped give 17 an ominous reputation in Italy.
The belief has practical cultural effects. Some Italian buildings, hotels and aircraft may omit room, floor or seat number 17, much as some English-speaking settings avoid 13. The superstition is particularly associated with Italy rather than with the whole of Europe.
The number’s reputation is not universal even within Italy, and it is a cultural convention rather than a mathematical property. Italian superstition also includes other regional beliefs, but 17 is the clearest national counterpart to the unlucky number 13.