Factoring Press using Stack

I made a vector stack, with the basic functions (push, pop, peek) and with it I want to do a prime factorization of a value. I did the program, but when I compile it, it stays in an infinite loop that I'm not identifying and does not return anything. Here are the codes:

Stack:

public class Pilha {

    public Object[] pilha;
    public int posicaoPilha;

    public Pilha() {
        this.posicaoPilha = -1;
        this.pilha = new Object[1000];
    }

    public boolean isEmpty() {
        if (this.posicaoPilha == -1) {
            return true;
        }
        return false;
    }

    public int size() {
        if (this.isEmpty()) {
            return 0;
        }
        return this.posicaoPilha + 1;
    }

    public Object peek() {
        if (this.isEmpty()) {
            return null;
        }
        return this.pilha[this.posicaoPilha];
    }

    public Object pop() {
        if (isEmpty()) {
            return null;
        }
        return this.pilha[this.posicaoPilha--];
    }

    public void push(Object valor) {
        if (this.posicaoPilha < this.pilha.length - 1) {
            this.pilha[++posicaoPilha] = valor;
        }
    }

    public void imprime() {
        if (isEmpty()) {
            System.out.println("Pilha vazia");
        }

        while (isEmpty() == false) {
            System.out.print(pop() + " ");                    
        }
    }
}

Primal Factor Function:

public class Exercicio5 {
    int fatorPrimo(int n) {
        int resultado = 1;
        Pilha pilha = new Pilha();

        while (n % 2 == 0) {
            n = n / 2;
            pilha.push(2);
        }

        for(int i = 3; i <= Math.sqrt(n); i=+ 2) {
            while(n % i == 0) {
                n  = n / i;
                pilha.push(i);
            }
        }

        while(!pilha.isEmpty()) {
            resultado = resultado * (int)pilha.pop();
        }

        while(!pilha.isEmpty()) {
            System.out.print(pilha.pop() + " * ");
        }

        return resultado;
    }
}

Test Stack:

public class TestaPilha {

    public static void main(String args[]) {
        Exercicio5 ex5 = new Exercicio5();

        int n = 3960;

        System.out.println(ex5.fatorPrimo(n));
    }
}

Note: Primal factor is to find prime values that are divisors of a n , which multiplied with each other, result in the value of n , such as 3960 = 11 * 5 * 3 * 3 * 2 * 2 * 2.