“2.1k” sounds silly in verbal communication, but I do use it when I’m writing. I always say “two thousand one hundred” but I know lots of people here (in Kansas) who say “twenty one hundred” and I don’t like that very much. And for trading because the short versions are popular on the website, I’d say 2.1k.
What happens after 10k followers on Instagram?
Once you have 10k followers, Instagram will make it easier for you to get people to your website via Stories with the swipe up to link feature. Swipe up is the only way to get a direct link from your Instagram to your other web properties. And, it’s available in STORIES, if you have 10k followers.