If superdeterminism is true your PRNG isn't random.
https://en.wikipedia.org/wiki/Pseudorandom_number_generator
"A pseudorandom number generator (PRNG), also known as a deterministic random bit generator (DRBG)..."
But the measurement setting (PRNG outcome) can be arbitrarily removed from the seed value (by combining PRNGs in various ways). So that doesn't sound very convincing to me.
If you mean true random, then, yes, superdeterminism does indeed mean that number is predetermined.
Math still works though - there is no way for someone to peek and see what that predetermined number is so it is still random for any observer.