N=(2+1)(2^2+1)(2^4+1)(2^8+1)
N=1(2+1)(2^2+1)(2^4+1)(2^8+1)
N=(2-1)(2+1)(2^2+1)(2^4+1)(2^8+1)

N=(2^2-1)(2^2+1)(2^4+1)(2^8+1)
N=(2^4-1)(2^4+1)(2^8+1)
N=(2^8-1)(2^8+1)
N=2^16-1<2^16=M
Vậy N

N= (2+1) (2^2+1) (2^4+1) (2^8+1)

   = (2^2 - 1) (2^2 + 1) (2^4 + 1) (2^8 + 1)

   = (2^4 - 1)(2^4 + 1)(2^8 + 1)

   =  2^16 - 1 < 2^16 

=> M > N