Because 21 is a multiple of 1, 3, 7 and 21.
The numeral '21' is evenly divisible by 21, 7, 3, and 1.
There is nothing that is divisible in 37 and 21. Because 37 is a prime number. However, 21 is divisible by 3 and 7.
a number is divisible by 12 if the number is also divisible by both 3 and 7. You mean a number is divisible by 21 if it is divisible by 3 and 7.
The divisibility rule for 3 is as follows: If the sum of the digits of a number is divisible by 3 then the number is divisible by 3. For example, the number 21 is divisible by 3 since 2+1=3, and 3 is divisible by 3. The number 49 is not divisible by 3 since 4+9=13, and 13 is not divisible by 3.
21 is not divisible by 2 nor 5, but it is divisible by 3. To be divisible by 2 the last digit must be even (one of {0, 2, 4, 6, 8}; the last digit 1 is not one of these, thus 21 is not divisible by 2 To be divisible by 3 sum the digits and if this total is divisible by 3, then so is the original number; the test can be repeated on the sum, so by repeatedly summing the digits of the totals until a single digit remains only if that single digit is 3, 6 or 9 is the original number divisible by 3. 21 → 2 + 1 = 3 which is divisible by 3 so 21 is divisible by 3. To be divisible by 5, the last digit must be 0 or 5. The last digit of 21 is 1 which is not 0 nor 5, thus 21 is not divisible by 5.
Because 21 is divisible by numbers other than 1 and 21. 21 is divisible by 1, 3, 7, 21
They are members of the infinite set of numbers of the form 21*k where k is an integer.
1, 3, 7, 21
21
63 ÷ 3 = 21
A prime number is any integer evenly divisible by only itself, and the number 1. Since 21 is divisible by 3 and 7, it is a composite number, not a prime number.No, 21 is not a prime number.21 is divisible by 1, 3, 7, & 21No. 21=3*7