AMC 12 2024a Problem 12

The first three terms of a geometric sequence are the integers $a, 720,$ and $b,$ where $a<720<b.$ What is the sum of the digits of the least possible value of $b?$

$\textbf{(A) } 9 \textbf{(B) } 12 \textbf{(C) } 16 \textbf{(D) } 18 \textbf{(E) } 21$