Can an 32-bit OS run on multiple 64-bit CPU cores?

[FlatAssembler]

Hey, guys!

So, I've tried to implement a MergeSort algorithm in standard C++11 that will run on as many CPU cores simultaneously as it can. You can see the source code here. However, I've noticed that if I run that program on 32-bit Windows 10 on my laptop (I have 32-bit Windows 10 and 64-bit Oracle Linux), here is the 32-bit Windows executable, it always claims to be running in a single thread. On the other hand, if I run it on 64-bit Linux on that same computer, it usually claims to run in 15 threads. What do you think is going on here? The processor in my laptop is Intel Core i5, 8th Generation. I know that running a 32-bit OS prevents the modern processor from using some registers, but I fail to see how it can possibly prevent it from using multiple CPU cores. The OS, these days, usually detects other CPU cores using ACPI, and it obviously shouldn't matter if the OS is 64-bit or 32-bit. But, apparently, it somehow does.

Corporate competition.

McDonald's and Burger King both sell burgers, and sure, the meet and buns are interchangeable, but they don't like the competition.

Err... Are you sure you posted this in the right thread?