Guilliman, Jaghatai Khan, the Lion, Russ, Vulkan, and Corax with their being disputes as to whether or not Dorn is dead. So thats six still living primarchs (seven with Dorn) of which one is active in current 40k.
Ok, I should say "active" primarchs. Others are presumably lost/dead/sleeping ?
Not saying I am an expert on what happened to Primarchs after HH but Guilliman was the only one present even if in stasis, right? For example Azrael don't know if there is Lion sleeping inside the Rock. Russ is on some EoT errand which could have negative impact on him or he could be dead etc.