The maximum values for an integer in SQL Server are:

-2147483648 through 2147483647

And the byte size is 4 bytes.

Other maximum values:

BigInt: -9223372036854775808 through 9223372036854775807 (8 bytes)
SmallInt: -32768 through 32767 (2 bytes)
TinyInt: 0 through 255 (1 byte)