SYNTAX_ERROR: line 1:10: Function to_number not registered

TO_NUMBER is not a function that works in Athena.

Rather use cast(value AS type) or try_cast(value AS type). For example try CAST(TO_CHAR(T1."INVOICE_DATE" ,'YYYY') AS int)

Reference: Please refer to Functions in Athena https://docs.aws.amazon.com/athena/latest/ug/presto-functions.html

SELECT cast(TO_CHAR(T1."INVOICE_DATE" ,'YYYY')) "c1",

Error line 1:49: mismatched input ')'. Expecting: <expression>