If by 'perfect number' you mean 'perfect SQUARE', then yes. 49 is an odd number and a perfect square.
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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.