345

345 = 3 x 5 x 23.

345 * 2³⁴⁵ - 345 - 2³⁴⁵ is a prime number.

345 is 1333 in base 6 and 113 in base 18.

345 is the sum of three positive cubes: 345 = 7³ + 1³ + 1³.

345 is the local telephone area code for the Cayman Islands.

Source: Prime Curios!