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
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.
Perfect Wedding was created on 2010-10-21.
Perfect - book - was created on 2007-08-21.
The Perfect Game was created on 2009-03-21.
work out and eat right
Mr Perfect - 2011 was released on: India: 21 April 2011 Kuwait: 21 April 2011 USA: 21 April 2011
Maude - 1972 The Perfect Marriage 1-21 was released on: USA: 13 March 1973
Yes it's 21 squared
A Perfect 36 - 1918 was released on: USA: 21 October 1918
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.
Perfect Strangers - 1986 Or Get Off the Pot 7-21 was released on: USA: 4 April 1992
Almost Perfect - 1995 The Hunted House 1-21 was released on: USA: 1 April 1996