2+ $[$ Prime numbers and their properties $]$

Four kids were discussing the answer to a problem.

Kolya said: "The number is 9."

Roman: "It's a prime number."

Katya: "It's an even number."

And Natasha said that the number is divisible by 15.

One boy and one girl answered correctly, while the other two were wrong. What is the actual answer to the problem?
If Kolya answered correctly, then both girls were wrong, since the number 9 is odd and does not divide by 15. This means that Roman gave the correct answer. But a prime number does not divide by 15, and the only even prime number is 2.

## Answer

2.