The accepted translation in English is "Long time, no see". However, there is a big difference in usage between "hisashiburi" and "Long time, no see". When I was in Japan, Japanese people would often say to me "hisashiburi" (if speaking in Japanese), or "Long time, no see" (if speaking in English) after not having seen me for a week or two. The use of "hisashiburi" in this situation is fine in Japanese, but in English it is not. In English, we generally only use "Long time, no see" after a gap of several months or years. This expression is therefore used far more often in Japanese than it is in English. Whenever my Japanese friends used to say to me in Japanese "James, konnichiwa, hisashiburi desu ne", I would always reply with something like "hisashiburi yo!", even if I had just seen them a mere couple of weeks before. But whenever we had the same conversation in English, for example starting with "Hello James. Long time, no see!", I would usually reply to them "No it isn't, we saw each other only two weeks ago". They were usually very confused.

"it's been a while" - maybe that's a good translation. But - usually it's only if you have not seen the person for more than a month. or if it's a long time = "it's been a long time" maybe we don't say it the same way Japanese do. But you can also write "it's been a while, how are you?" - on Italki - if, for example, you have not had a message for over a month or more.