989 = 23 x 43.
989 is the smallest number so that it and its reverse are divisible by 43.
989 is 33131 in base 4 and 12424 in base 5.
989 is one of the integers generated by the following sieve: Keep first number, drop every second, keep first, drop every third, keep first, drop every fourth, and so on: 0, 1, 3, 5, 9, 11, 17, 21, 29, 33, . . . , 989, . . .
Halley's Comet was visible from Earth in the year 989.
