Tuesday, May 15, 2012

2219

2219 = 7 x 317. It is the product of two primes whose sum is a perfect square (A141755): 7 + 317 = 324 = 182.

2219 is the number of 14-hexes with reflectional symmetry (A002215). It is also the number of restricted hexagonal polyominoes with 7 cells (A002212).

2219 is the number of incongruent ways to tile a 5 x 66 room with 1 x 2 Tatami mats, with at most three Tatami mats meeting at a point (A068930).

2219 is a number of the form ab + cd, where a, b, c, and d are the first four primes (A168349): 2219 = 25 + 37.

2217 = 3 x 739, 2218 = 2 x 1109, and 2219 are all semiprimes (A115393).


Source: What's Special About This Number?

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