Answer:
Since [tex]64= 2^6[/tex], you have the following arrangements.
Optional: [tex]64 \times 1[/tex] (and it's mirror version [tex]1 \times 64[/tex], if you want to consider a long strip of bottles a rectangle. Technically it is, but it's open to interpretation.
[tex]32 \times 2[/tex] and it's mirror [tex]2 \times 32[/tex];
[tex]16 \times 4[/tex] and it's mirror [tex]4 \times 16[/tex];
Optional: [tex]8 \times 8[/tex]. Since a square is a rectangle with extra limitations.
