If $$N = 4^{11} + 4^{12} + 4^{13} + 4^{14}$$, then how many positive factors of $$N$$ are there?
$$N=4^{11}+4^{12}+4^{13}+4^{14}$$
or, $$N=4^{11}\left(1+4^1+4^2+4^3\right)=4^{11}\times5\times17\ .$$
So, $$N=2^{22}\times5\times17\ .$$
Case1 (1 factor) :
$$2,2^2,2^3,....,2^{22},5,17\ $$
Total 24 factors .
Case2 (2 factors) :
$$2\times5,2\times17,\ 2^2\times5,2^2\times17,....,5\times17\ .$$
Total $$2\times22+1=45\ $$factors .
Case3 (3 factors) :
$$2\times5\times17,\ 2^2\times5\times17,.......,2^{22}\times5\times17\ .$$
Total $$22$$ factors .
Case4 :
1 is also a factor .
Total number of factors =Â $$24+45+22+1=92\ .$$
A is correct choice.
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