\[2520 = 2 \bullet 1260 = 2 \bullet 2 \bullet 630 =\]
\[= 2 \bullet 2 \bullet 2 \bullet 315 =\]
\[= 2 \bullet 2 \bullet 2 \bullet 3 \bullet 105 =\]
\[= 2 \bullet 2 \bullet 2 \bullet 3 \bullet 5 \bullet 21 =\]
\[= 2 \bullet 2 \bullet 2 \bullet 3 \bullet 5 \bullet 7 \bullet 3 =\]
\[= 2^{3} \cdot 3^{2} \cdot 5 \cdot 7\]