#MathProblemOfTheDay: Halloween Costume Puzzle

katherinebellafioresanden_12107674_1669645876584186_1503028030_n

Remains of my last minute Halloween costume.

I dressed up as a puzzle. I taped numbers all over my pants. They were sorted into 2 clumps: one clump on each leg.  All the numbers on my left leg had something in common, and all the numbers on my right leg had something in common.

Hint: none of these numbers is divisible by 3.

Can you figure out why the numbers are sorted this way?