There are several answers:

51 hrs (2 days 3 hrs); 111 hrs (4 days 15 hrs); 171 hrs (7 days 3 hrs); 231 hrs (9 days 15 hrs);
291 hrs (12 days 3 hrs); 351 hrs (14 days 15 hrs);
411 hrs (17 days 3 hrs); 471 hrs (19 days 15 hrs);
531 hrs (22 days 3 hrs); 591 hrs (24 days 15 hrs);
651 hrs (27 days 3 hrs)