(Telecompaper) Facebook maintained its double-digit growth in the second quarter, growing revenues 61 percent year-on-year to USD 2.91 billion. The number of daily active users on the social network was up 19 percent to 829 million, and monthly users increased 31 percent to 1.07 billion. Facebook's strongest growth was in mobile, where the number of active daily users rose 39 percent to 654 million. Mobile accounted for 62 percent of its USD 2.68 billion in advertising revenue in the quarter, up from 41 percent in the year-earlier period. Net profit rose to USD 791 mllion or 30 cents a share, from USD 333 million or USD 0.13 per share in the second quarter of 2013. The company invested USD 469 million in the quarter, while generating free cash flow of USD 872 million. Facebook finished the quarter with total cash of USD 13.96 billion.