Last year she got a Mercedes Benz SUV from her boyfriend as a 20th birthday gift. But yesterday Hilary Duff was spotted keeping things a little more low-key for her big 2-1.

The paparazzi caught up to the “War, Inc.” hottie as she meandered around New York City with beau Mike Comrie, stopping into a children’s bookstore as part of her 21st birthday activities.

And Miss Duff looked casual-yet-sexy in a white tank top with a silver scarf, teamed with a pair of slim fit jeans and some knee-high Burberry boots.

As previously reported by the Gossip Girls, Hilary’s mom Susan Duff recently won a judge’s ruling to have her father Bob Duff go halves on a $25,000 birthday bash for her.

Gossip Girls

Enjoy the pictures of Hilary Duff out for her birthday meal (September 28).