What is the significance of "6,741", the title of an upcoming episode in the fifth season of Person of Interest?

It's the number of different simulations run by Samaritan assets on Sameen Shaw. The purpose is not explicitly defined, but from context within the episode it seems that:

She is being run through the same scenario multiple times, after changes/updates are made to a chip inserted behind her ear. As one operative says to Greer in the room where Shaw is held "This time it took a whole extra hour for her to shoot you in the head", it can be inferred that the purpose of these scenarios is to achieve a chip capable of controlling Shaw to the extent that she can be used as a Samaritan asset to find/betray the Machine, Finch, Reese and Root.

However, that's just my interpretation - I'm sure the storyline will develop further in future episodes to confirm or otherwise.

It is the number of simulation that Sameen is subjected to by samaritan operatives to extract information about Team Machine and its latest base of operations.

The number of simulations Samaritan runs on Shaw trying to compromise her and turn her into a Samaritan operative after rendering her paralysed in a quasi-vegetative state. By inserting a chip to her ear (similar to a cochlear implant in Root's ear), they try to feed her the same scenario multiple times hoping to revive her memories and extract the location of Team Machine and its members.