The number of IPv4 prefixes in the global BGP table is approaching the limit of many Cisco products, such as 7600/6500 RSP720/Sup720 and some ASR1000, which may hold a maximum of ~500K routes in their FIB (the Forwarding Information Base, where only best paths are stored).
These routers can usually handle a bigger load of prefixes, they can also be used to receive the full BGP table from many upstream providers concurrently, but they can’t manage more than 500/512K entries in their RIB or FIB.