The number that comes after 999 trillion is 999 trillion and one! You are likely looking for quadrillion, however. After that is quintillion, sextillion and septillion. You can find
http://answers.ask.com/Fashion_and_Beauty/Jewelry/...

A quadrillion comes after a trillion. ChaCha again!
http://www.chacha.com/question/whatcomesafter99...

In the short scale, 999 trillion is 999,000,000,000,000, and the number after that is 999,000,000,000,001. In the long scale, 999 trillion is 999,000,000,000,000,000,000, and the
http://wiki.answers.com/Q/What_number_comes_after_...

It is not accurate, but I suppose you are asking what comes after trillions, and the answer is a quadrillions. It goes, millions, billions, trillions, quadrillions, quintillions,
http://answers.yahoo.com/question/index?qid=200901...
