I come up with:
86,400 seconds in a 24-hour day
1,460 days from Jan 1 2013 to Dec 31 2016 (not accounting for leap year)
126,144,000 total seconds
@ $16,666 per second, that comes to $2,102,315,904,000
Starting at $16,275,194,500,000 and adding 2,102,315,904,000 you end up with $18,377,510,404,000.
That does not take into account the impending rise in SS or government expenditures related to a rise in Medicare recipients as the boomers retire over the next few years. It also does not take into account the government costs of ACA.
From 2010-2019, the CBO projects a budget deficit totalling over $7 trillion (link here:
http://www.cbo.gov/sites/default/files/cbofiles/ftpdocs/105xx/doc10521/08-25-budgetupdate.pdf). If that holds true, we're already at about $4.5 trillion, leaving about $2.5 trillion remaining. If they're correct, the calculations above seem right.
Then again, that assumes that all of the tax cuts are extended, and assumes the economy grows at a much faster rate than it is currently growing...but keep in mind that growth projections for the economy have been almost exclusively downgraded over the last 18 months.