278

278 = 2 x 139.

278 is the sum of the first 18 nonprimes.

278 has the representation 2⁸ + 22.

278 is the closest integer to 6^π.

278 is 545 in base 7.

Telephone area code 278 serves Ann Arbor, Michigan, and the surrounding area.

Source: What's Special About This Number?