The isainfo command can be used to determine if a Solaris system has been configured to run in 32 or 64 bit mode.

Run the the following command:

isainfo -v

If the system is running in 32 bit mode, you will see output as follows:

32-bit sparc applications

On a 64 bit Solaris system, you will see the following:

64-bit sparcv9 applications
32-bit sparc applications