program BT;
uses crt;
var n,i,d,x,y,t,kt: integer;
st,s: string;
Begin
clrscr;
repeat
write('Nhap n: '); readln(n);
until (1000<=n) and (n<=9999);
str(n,st);
d:=length(st);
t:=0;
for i:=1 to d do
begin
val (st[i],x,y);
t:=t+x;
end;
writeln('Tong cac chu so cua ',n,' la: ',t);
if t>1 then
begin
for i:=2 to trunc(sqrt(t)) do
if t mod i=0 then kt:=1;
if kt=0 then writeln('Tong 4 chu so cua ',n,' la so nguyen to')
else writeln('Tong 4 chu so cua ',n,' khong la so nguyen to');
end;
s:=' ';
for i:=d downto 1 do s:=s+st[i];
while s[1]='0' do delete(s,1,1);
writeln(n,' viet nguoc lai la: ',s);
readln;
end.
