713.
403
Because the correct sum of 305 and 98 is 403.
402, 403, 404
403 is divisible by 1, 13, 31 and 403.
The positive integer factors of 403 are: 1, 13, 31, 403
403 is composite. It can be evenly divided by 13: 403/13 = 31.
403 is divisible by no number
403
It is: 403 = CDIII
87 * 403 = 35,061
781