An ace can be the lowest card of a straight (ace, 2, 3, 4, 5) or the highest card of a straight (ten, jack, queen, king, ace), but a straight can't "wrap around"; a hand with queen, king, ace, 2, 3 would be worthless (unless it's a flush).

The Blackjack 21 app works well with both Android and iOS, as it was created by AbZorba games.

Yes, you can play for, and win, real money when playing blackjack on mobile devices. It works in exactly the same way as it would on a desktop online casino, and the same real money prizes are up for grabs too.