Power of two
= Power of two
{title2=$2^k,\quad k\in\mathbb Z_{\geq0}$}
= Powers of two
{synonym}
= Powers of 2
{synonym}
= Power of 2
{synonym}
In this <positive integer> context, a <power of two> is $2^k$ for a <nonnegative integer> $k$, giving $1,2,4,8,\ldots$. Allowing negative or real <exponents> gives a broader meaning of <exponentiation>, which is not intended in the integer divisibility criteria here.