More than 100 million people worldwide are Amazon Prime subscribers.
Amazon CEO Jeff Bezos let that secret slip to shareholders in a letter released Wednesday.
Prime subscribers pay a yearly fee to get a number of benefits, including free two-day shipping and access to Amazon's streaming service.
Despite his Amazon Prime reveal, Bezos is still being cagey with some other company numbers. He used the "tens of millions" description to tell shareholders about the number of customers using Amazon Music and Prime Wardrobe.
Additional reporting from Newsy affiliate CNN.