Not especially a trojan file scanner, but a general security check is available here: http://onlinecheck.emsisoft.com
That's right. Sum the values and you will get the 24216 signatures. ;) Signatures are always more than unique malwares. E.g. TrojanXY...
Let me correct it: The a² signature database currently contains: - 6746 unique trojans (server, client and tools of one trojan are ONE unique)...
Separate names with a comma.