It is unknown whether an odd perfect number actually exists. If an odd perfect number exists it will be extremely large, that is in excess of 10300.
No. Because 7 is not even a perfect number; it is conjectured (not proven) that there are no odd perfect numbers only even ones and 7 is an odd number - it has been proven that if there is an odd perfect number it has to be extremely large, much-much-much larger than 7)
It is not yet known:Whether there is an infinite number of even perfect numbersWhether there is any odd perfect number
81 is; Natural number, Perfect-square number, Perfect 4th root number, Perfect totient number, Odd Number, Composite Number, etc.
It is 1! = 1.
It is unknown whether an odd perfect number actually exists. If an odd perfect number exists it will be extremely large, that is in excess of 10300.
An odd number.
A perfect square has an odd number of factors.
-1 is an odd number but not a perfect square.
if a number has an odd number of factors it would be a perfect square
if a number has an odd number of factors it would be a perfect square
1 is odd and a perfect square.
Perfect squares are numbers with an odd number of factors.
I would call an odd number factor a factor that is an odd number. I would call a number with an odd number of factors a perfect square.
A perfect square has an odd number of factors. Factors of numbers always come in pairs -- except for perfect squares. Since the square root of a perfect square is listed only once on the list of factors, it results in a list with an odd number of factors.
a perfect square
A perfect square.