[chryuop]

I was writing to a friend and to cut it short I was kidding and said "what kind of brother are you...". So I wrote どんな兄ちゃん...and he said the correct way to say it is なんという兄ちゃん...
I am a little confused. I checked the dictionary and for なんという it gives examples like "how beautiful" or similar...
Any help is appreciated.