My teacher gave a math riddle i have exactly 3 factors the number before and after me is divisible by 2 (not prime) i am a factor of 100 what am i this is due first thing in the morning

The factors of 100 = 1, 2, 4, 5, 10, 20, 25, 50, 100

1 has only 1 factor (1 itself)
2,5 is prime and has 2 factors each
10 has 4 factors (1,2,5,10)
20 has 6 factors (1,2,4,5,10,20)
25 has 3 factors (1,5,25)
50 has 6 factors (1,2,5,10,25,50)

The answer is 25