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 2015-06-23, 02:02 #2 Batalov     "Serge" Mar 2008 Phi(4,2^7658614+1)/2 59·157 Posts Ok, let's give it a try: 2^n is an even number. Sum of its divisors (1 and many even numbers) is an odd number. Hence, 2^n cannot be equal sum of its divisors. $\qed$ Last fiddled with by Batalov on 2015-06-23 at 03:28 Reason: its != it's