9966

9966 = 2 x 3 x 11 x 151. It has exactly four distinct palindromic prime factors (A046402).

9966 is the largest four-digit strobogrammatic number (A000787).

9966 is a number m such that (6 x m)⁵ is a sum of a twin prime pair (A173560).

9966 is an integer of the form 1/3 + 2/3 + 3/3 + 5/3 + 7/3 + 11/3 + 13/3 + 17/3 + ... (A182155).

Source: What's Special About This Number?