How do I properly

i'm new to C programming and I have an assignment coming up which I was struggling to work on. My question is that I want to ask the user to Enter in an International Standard Book Number (ISBN) but IF the number does not satisty 9780306406157 then it is an invalid ISBN number. I tried my code but for some odd reason anytime if the user enters 9780306406157 it gives me an Invalid ISBN number which is wrong... Here is my code,

#include<stdio.h>
int main()
{
    int isbn;

    printf("Enter 13 digits of ISBN-13: ", isbn);
    scanf("%1d", &isbn);

    int isbn_13 = 9780306406157;

    if (isbn == isbn_13) 
    {
        printf("Valid ISBN number.");
    }

    else if (isbn != isbn_13) 
    {
        printf("Invalid ISBN number. ");
    }
    return 0;

}