Can simple data types be stored on the heap in memory?

In Java, primitive data types are usually stored on the stack if they are local variables, or inside an object on the heap if they are fields of an object. That is, the values of primitives themselves can reside in the heap if they are part of an object placed on the heap.

For example:

class Example {
    int number; // object field, stored in heap with the object
}

public class Main {
    public static void main(String[] args) {
        int localVar = 10; // local variable, stored on stack
        Example obj = new Example(); // object on heap
        obj.number = 5; // primitive inside an object on heap
    }
}

Thus, primitives themselves are not allocated separately on the heap, but can be part of objects stored on the heap.