Rishabhanatha (Adinath) is said to have lived for 8,400,000 purva. In Jain cosmology, a purva is an extremely large unit of time, so this figure is symbolic and meant to express an immense lifespan. Different Jain traditions may recount minor narrative details, but both Śvetāmbara and Digambara sources uphold the idea of his extremely long life. You can read more here