[detaro]

I assume you mean the largest integer factorized: factorizing a prime is pretty pointless.

376289 per https://crypto.stackexchange.com/a/59796, depending what you count and don't count.

[Aardwolf]

Even better would be to ask what is the largest integer that has two large prime factors that was factored, since factoring e.g. a large power of 2 is easy