388

388 = 2² x 97.

388 has a representation as a sum of two squares: 388 = 8² + 18².

The number 388 followed by 388 sevens is a prime number.

388 is the maximum value of n so that there exist 6 denominations of stamps so that every postage from 1 to n can be paid for with at most 6 stamps.

The Junkers Ju 388 was a German World War II aircraft.

Source: Prime Curios!