What is the product of all the prime factors of 21?
Options.
A) 20	B) 21	C) 18	D) 17	E) 16
factors : 1,3,7,21   3*7= 
<gadget id="calculator">3*7</gadget>
<output>21</output>
21   Answer : 21
<result>B</result>
What is the product of all the prime factors of 21?