The maximum number of Bitcoins will be 21 million. LTC was the first to figure it. By increasing the speed 4 times (4 *supply of Bitcoins) they have upped the speed of mining Bitcoins. The total number of LTC will be 84 million. Every 2.5 minutes a Litecoin is mined and 25 coins are generated. Every day 14,400 LTC are mined.
At present, there are about 53 million units and 31 million units still remain to be mined.