16 and 81 have 5 factors
The number that is greater than 12, less than 40, and has exactly 3 factors is 25. A number has exactly 3 factors if it is the square of a prime number. In this case, 25 is the square of the prime number 5 (5² = 25), and it has the factors 1, 5, and 25.
625 has five factors.
A number that has exactly an odd number of factors is a power of another number. A number between 10 and 30 that is a power is 16. It is 24 (as well as 42) and its factors are 1, 2, 4, 8, and 16.
625 has five factors.16 does, among others.
Indeed, the number 16 has 5 factors, 1, 2, 4, 8, and 16.
A prime number, like 2, 3 or 5.
16
16
16 does.
16
A prime number has exactly two factors.
16