4347

4347 = 3 x 3 x 3 x 7 x 23.

4347 is a heptagonal number (A000566). It is also a pentagonal number (A049452).

4347 is the concatenation of the 27th and 28th primes (A045533).

4347 is a value of n for which 2n and 5n together use each of the digits 1 to 9 exactly once.

4347 is the number of regions in a regular 63-gon that are octagons (A067155).

4347 divides 22¹⁸ - 1.

Source: Number Gossip