This is an RSA challenge called '768'. So, we search up [RSA 768](http://bfy.tw/FOES) on Google, and the first result that comes up is a Wikipedia article about RSA numbers. The one of interest to us is [RSA-768](https://en.wikipedia.org/wiki/RSA_numbers#RSA-768) and we get the factors. After getting the factors, decrypting is pretty easy and we get the flag: `tpctf{omg_b1c_m0dulus}`.