This Thursday, Oct. 17, the U.S. Treasury Department will run out of money and will no longer have the ability to borrow the funds needed to pay the U.S. government's bills.

The federal debt ceiling of $16.699 trillion was actually reached on May 19, but the engine of government was able to keep chugging along by accessing an extra $412 billion through so-called "extraordinary measures," according to the Washington Post. Having now maxed out all available resources, however, the U.S. government will no longer be able to meet any debt obligations, including billions of dollars in Social Security, military personnel, Medicare and other payments that are due Nov. 1.

If $16.699 trillion seems like a hard figure to wrap your head around, you're not alone. It's difficult for most people to have a concept of even a much smaller amount, like the proposed $700 billion Treasury bailout for failing bank assets, which was passed by Congress and signed into law in 2008. (The amount was reduced to $475 billion in 2010, with the signing of the Dodd-Frank Act.) [The 18 Weirdest Effects of the Government Shutdown]

A trillion dollars' worth of $1 bills stacked on top of one another would reach about 67,000 miles (108,000 kilometers) high, according to Freakonomics. Therefore, $16.699 trillion of stacked $1 bills would be more than 1 million miles (1.6 million km) high — enough to stretch from the Earth to the moon four times and still have money left over.

But most people have never been to the moon, so it might be easier to grasp that sum by spreading all those trillions around: If each of the United States' 317 million people took up his or her share of $16.699 trillion, each American man, woman and child would be in debt to the tune of about $52,678 — slightly more than the current U.S. mean annual household income of $52,100.

Perhaps it's unfair to soak the average taxpayer with that kind of debt. So if you look to plutocrats for help, you'll find that Bill Gates is worth about $67 billion, according to the 2013 Forbes list of billionaires. It would take 250 times Bill Gates' fortune — far more than the bankrolls of Gates, Warren Buffet, Charles and David Koch, Michael Bloomberg and Mark Zuckerberg combined — to equal the $16.699 trillion debt ceiling. In fact, if each of the Earth's 7 billion-plus people coughed up $2,000, there would be still be a shortfall of more than $2 trillion.

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There is still time for Congress to act to prevent the government from defaulting on its obligations. As Winston Churchill famously quipped, "You can always trust America to do the right thing — after it has exhausted all other options."

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