Can MariaDB or MySQL cast as bigint, getting an error: ... right syntax to use near 'bigint)'?
Silently? Let's try:

CREATE TABLE g
   AS SELECT CAST('2147483699' AS int);


MariaDB 10.1.32, default sql_mode (non-strict)


  Query OK, 1 row affected, 1 warning (0.19 sec) Records: 1  Duplicates:
  0  Warnings: 1


And the warning is:


  | Warning | 1264 | Out of range value for column 'CAST('2147483699' AS int)' at row 1 |


Yes, selecting from the table is interesting, but not surprising given the warning.

(I don't have a MariaDB 10.2 instance at the moment, but testing on dbfiddle.uk indicates it too fails, though again not silently.)

MariaDB 10.3.6, default sql_mode (strict)

No warnings.

select * from g;

Gives:

+---------------------------+
| CAST('2147483699' AS int) |
+---------------------------+
|                2147483699 |
+---------------------------+
1 row in set (0.000 sec)


And the column is indeed created as bigint(10).

MySQL 8.0, both the default strict and non-strict sql_mode


  ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'int)' at line 2


Computer says no.

Conclusion

Can MariaDB or MySQL cast as bigint? As we have seen, yes, MariaDB 10.3 can (though it's not GA yet ... but surely any day now it will be). However, it can only cast as bigint implicitly. You can't explicitly cast as bigint, just like you can't cast as varchar (but see MDEV-11283), text, float, tinyint etcetera. There are only a limited number of datatypes you can cast to. This is not well documented, but CAST appears to support only the same datatypes as listed for the CONVERT function.