On minimal distance between q-ary bent functions

The minimal Hamming distance between distinct $p$-ary bent functions of $2n$ variables is proved to be $p^n$ for any prime $p$. It is shown that the number of $p$-ary bent functions at the distance $p^n$ from the quadratic bent function is equal to $p^n(p^{n-1}+1)\cdots(p+1)(p-1)$ as $p>2$.