WRITE A PLSQL BLOCK CHECK WETHER GIVEN NUMBER IS STRONG OR NOT?

DECLARE
N INTEGER:=&N;
R NUMBER;
S NUMBER:=0;
I NUMBER;
M NUMBER;
F NUMBER:=1;
BEGIN
M:=N;
WHILE(N!=0) LOOP
R:=MOD(N,10);
FOR I IN REVERSE 1..R LOOP
F:=F*I;
END LOOP;
S:=S+F;
N:=TRUNC(N/10);
F:=1;
END LOOP;
IF (S=M) THEN
DBMS_OUTPUT.PUT_LINE(M||' '||'IS A STRONG NUMBER');
ELSE
DBMS_OUTPUT.PUT_LINE(M||' '||'IS NOT STRONG NUMBER');
END IF;
END;