398

398 = 2 x 199.

398 is the number of integers with integer complexity 22.

398 is the solution to the postage problem with two denominations and 37 stamps (A014616).

398 is a number n such that n¹⁰ + n⁹ + n⁸ + n⁷ + n⁶ + n⁵ + n⁴ + n³ + n² + n + 1 is prime (A162862).

398 is the smallest even number with digit sum 20 (A069532).

398 and the 398th prime (2729) have only the digit 9 in common (A107940).

Source: What's Special About This Number?