A number smaller than 19 that has more factors than 21 23 25

21 has four factors: 1, 3, 7 and 21. 23 is a prime number so it only has two factors: 1 and 23. 25 has three factors: 1, 5 and 25. To fulfil the criteria, therefore, a number must be smaller than nineteen and have more than four factors. Such numbers include 12, 16 and 18.