How can I remember scales?

When learning scales on the piano, I had memorized the circle of fifths in music theory (which has helped me so much in all my years in music, highly recommended!). I then would sing all the scales on letter names instead of solfege. I had purchased a pitch pipe, which was not very expensive, in order to give a starting pitch if I wasn't near a piano, like at work or when I'm doing house chores.