Are all the binaries 64 bit ?

I am using Fedora core 4, 32 bit edition on my AMD Athlon 64 bit processor. I am planning for the 64 bit edition. I have downloaded Mandriva Linux 64 bit edition. But some programs of it actually 32 bit. (tested for gcc which gives sizeof(int) = 4). Now a question is arising in my mind, that is, are all the binaries of Fedora core 64 bit edition is actually 64 bit ? How we can test that the binary is in 32 bit or 64 bit format ?