What is the product of all positive factors of 21? Choose the correct choice from the following answers.
A) 39	B) 324	C) 441	D) 451	E) 551
Positive factors of 21 are 1, 3, 7, 21.   Positive factors of 21 is:   21*7*3= 
<gadget id="calculator">  21*7*3</gadget>
<output>441</output>
441   Answer: 441
<result>C</result>
What is the product of all positive factors of 21?