difference between int and int64 code example

Example 1: Int64

ulong ulNumber = 163245617943825;
try {
   long number1 = (long) ulNumber;
   Console.WriteLine(number1);
}
catch (OverflowException) {
   Console.WriteLine("{0} is out of range of an Int64.", ulNumber);
}

double dbl2 = 35901.997;
try {
   long number2 = (long) dbl2;
   Console.WriteLine(number2);
}   
catch (OverflowException) {
   Console.WriteLine("{0} is out of range of an Int64.", dbl2);
}
   
BigInteger bigNumber = (BigInteger) 1.63201978555e30;
try {
   long number3 = (long) bigNumber;
   Console.WriteLine(number3);
}
catch (OverflowException) {
   Console.WriteLine("{0} is out of range of an Int64.", bigNumber);
}    
// The example displays the following output:
//    163245617943825
//    35902
//    1,632,019,785,549,999,969,612,091,883,520 is out of range of an Int64.

Example 2: int32 vs int64

Int32 and Int64 are defined by their names. Int32 is a signed, thirty-two byte integer value (4 bytes), and an int64 is a signed, sixty-four bit integer value (8 bytes). Int32 has a min/max of 2.147 billion and int64 has a min/max of 9223 with a lot of zeroes