find the number of factors of 243243 which are multiples of 21?
Factors of 243243 =1, 3, 7, 9, 11, 13, 21, 27, 33, 39, 63, 77, 81, 91, 99, 117, 143, 189, 231, 243, 273, 297, 351, 429, 567, 693, 819, 891, 1001, 1053, 1287, 1701, 2079, 2457, 2673, 3003, 3159, 3861, 6237, 7371, 9009, 11583, 18711, 22113, 27027, 34749, 81081, 243243
Answer: 48