The first four perfect numbers are:
These were the only perfect numbers known to ancient mathematicians. Some other perfect numbers include:
Even Perfect Numbers
It is conjectured that there are are infinitely many Mersenne primes and hence infinitely many even perfect numbers. No odd perfect numbers are known, and any that do exist must be greater than . It is conjectured that there are none. No one has been able to prove or disprove these conjectures.