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The definition of perfect number is a number x such that its factors, excluding itself, when summed up form a total of x.
An example of it is 6:
Its factors (excluding itself) are 1,2 and 3
1+2+3=6
Amazing
Another is 28:
Factors excluding itself: 1,2,4,7 and 14
1+2+4+7+14=28
Now knowing what a perfect number is, let's check 21
Factors of 21 (excluding itself): 1,3 and 7
1+3+7=11
11 is not equal to 21
So 21 is not a perfect number
What else can I help you with?
What two square numbers total 21?
There is no pair of perfect squares that sums to 21. And the question is pointless if it is not about perfect squares because in that case there are infinitely many answers.There is no pair of perfect squares that sums to 21. And the question is pointless if it is not about perfect squares because in that case there are infinitely many answers.There is no pair of perfect squares that sums to 21. And the question is pointless if it is not about perfect squares because in that case there are infinitely many answers.There is no pair of perfect squares that sums to 21. And the question is pointless if it is not about perfect squares because in that case there are infinitely many answers.
How do you get perfect body with perfect figure at the age of 21?
work out and eat right
When was The Perfect Game created?
The Perfect Game was created on 2009-03-21.
When was Perfect Wedding created?
Perfect Wedding was created on 2010-10-21.
When was Perfect - book - created?
Perfect - book - was created on 2007-08-21.
What are the release dates for Mr Perfect - 2011?
Mr Perfect - 2011 was released on: India: 21 April 2011 Kuwait: 21 April 2011 USA: 21 April 2011
What are the release dates for Maude - 1972 The Perfect Marriage 1-21?
Maude - 1972 The Perfect Marriage 1-21 was released on: USA: 13 March 1973
Is 441 a perfect square?
Yes it's 21 squared
What are the release dates for A Perfect 36 - 1918?
A Perfect 36 - 1918 was released on: USA: 21 October 1918
Why 21 is not a perfect number?
First, you want to know the definition of a perfect number: A perfect number is an integer which is equal to the sum of all its positive integer divisors that are less than itself. Example: The positive integer divisors of 6, less than 6, are 1, 2, and 3. The sum of those divisors is 1 + 2 + 3 = 6. Therefore, 6 is a perfect number. Now, 21 does not meet this definition and therefore is not a perfect number. Let's try it. There are three positive divisors of 21, namely, 1, 3, and 7, that are less than 21, itself. (There are no others.) But the sum of these divisors is 1 + 3 + 7 = 11, which is not equal to 21. Therefore, we confirm that 21 is not a perfect number.
What are the release dates for Perfect Strangers - 1986 Hello Elaine 2-21?
Perfect Strangers - 1986 Hello Elaine 2-21 was released on: USA: 1 April 1987
What are the release dates for FamTeam - 2010 Practice Makes Perfect 1-21?
FamTeam - 2010 Practice Makes Perfect 1-21 was released on: USA: 7 February 2011
