c++ Integer overflow in spite of using unsigned int and modulo operations

        int orders=1000000000;
        int mod=pow(10,9)+7;
        unsigned int total=4294967295; 
        total=(orders*(orders+1))%mod;
        total/=2;
        return total;       

expected Answer= 21

BUT getting

runtime error: signed integer overflow: 1000000000 * 1000000001 cannot be represented in type 'int'

I also tried

        int orders=1000000000;
        int mod=pow(10,9)+7;
        long long total=0LL; 
        total=(long long)(orders*(orders+1))%mod;
        total/=2;
        return total; 

Same error

//Compiled with clang 11 using the latest C++ 17 standard.

May I know why this is happening? I thought maybe long long is getting truncated to int hence the 0LL, But still that didn't solve the issue.

When tried on other compiler, getting output

for 1st code:

-243309312

for second peice of code:

1904174336