At His Death in 2014 Nathan Owned the Following Property

At his death in 2014 Nathan owned the following property: $\begin{array}{c}\begin{array}{lll}\frac{\text { Description}}\\\\\text{Real estate}\\\text{Cash, stock, and bonds}\\\text{Personal property}\\\end{array}\begin{array}{lll}&\end{array}\begin{array}{lll}\frac{\text { Value }}\\\\{\$ 5,000,000} \\10,500,000 \\200,000\\\end{array}\end{array}$ The real estate is subject to a $1,700,000 mortgage and Nathan made taxable gifts in 2009 totaling $2 million at which time he offset the gift tax with a unified credit (exemption equivalent of $2 million). Nathan has never been married. What is the amount of his estate tax due?