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Demi Lovato is 21 - see 21 photos of birthday girl's cutest smiles

<div class="meta "><span class="caption-text ">Demi Lovato poses with fellow &#39;X Factor&#39; judge Simon Cowell at FOX&#39;s Upfront Presentation in New York on May 13, 2013. (Kristina Bumphrey &#47; Startraksphoto.com)</span></div>
March 27, 2014 3:33:58 PM PDT