The 400 richest Americans are now worth a combined USD 2 trillion, according to Forbes.

That sets a record, Forbes said, and marks a jump from last year`s total of USD 1.7 trillion.

The average net worth of a Forbes 400 member is now USD 5 billion-also the highest ever. And the costs of being part of the 400 Club rose to USD 1.3 billion.

But it`s the USD 2 trillion number that remains the most interesting. The 400 richest are now worth more than the GDPs of many nations-and they are worth more than most governments spend or tax.

Here is some perspective on what the 400 richest Americans are really worth.

USD 2 trillion is more than the combined net worth of half of all Americans. The bottom half, of course.

USD 2 trillion is more than the annual GDP of Italy, Mexico or Canada.

USD 2 trillion is equal to the Federal Reserve's holdings of publicly traded US Treasurys.

USD 2 trillion is the estimated size of the underground economy, mostly unreported income.

USD 2 trillion would fund all government spending through July of this year.

USD 2 trillion is equal to about two-thirds of all taxes to be collected in the US for 2013.

USD 2 trillion would pay for all of the existing home sales in the US in 2012 AND2013 year-to-date.

-By CNBC`s Robert Frank. Follow him on Twitter @robtfrank.

Copyright 2011 cnbc.com

First Published:Sept 17, 2013 4:17 PM IST