Is 21,063 divisible by three? if it is, write a number as a product of three and another factor if not, explain

Twenty-one thousand and sixty-three divided by three is 7021

First, take any number (for this example it will be 492) and add together each digit in the number (4+9+2 = 15). Then take that sum (15) and determine if it is divisible by 3. The original number is divisible by 3 (or 9) if and only if the sum of its digits is divisible by 3 (or 9).If a number is a multiplication of 3 consecutive numbers then that number is always divisible by 3. This is useful for when the number takes the form of (n * (n - 1)*(n + 1))Example: 492 (The original number). 4 + 9 + 2 = 15 (Add each individual digit together). 15 is divisible by 3 at which point we can stop. Alternatively we can continue using the same method if the number is still too large: 1 + 5 = 6 (Add each individual digit together). 6 ÷ 3 = 2 (Check to see if the number received is divisible by 3). 492 ÷ 3 = 164 (If the number obtained by using the rule is divisible by 3, then the whole number is divisible by 3)

I'm sure the answer is a