Toddlers are fascinated by other children. Yours may even ignore you if another child is around. In fact, studies have shown that if you put a 12-month-old and a 24-month-old together, they meet in the middle: The older child will probably regress in her play to 15 months, while the 12-month-old's ability will skip ahead to 15 months. That way they can easily play alongside each other.
This absorption in other children is understandable, considering how important peers are at this age. Even though 22-month-olds still tend to play in parallel with other children, rather than interacting directly with them, your child will learn a lot by imitating, watching, and even struggling with other kids.
Organize or join a play group to help your child get the interaction she needs. At this age, a two-hour play period (including a snack) is about maximum for learning purposes.
Get more information on your child's style of play.