The last reactor to shutdown was Unit 3 in December 2000. The whole facility has been undergoing cleanup and decommissioning since.
https://en.wikipedia.org/wiki/Chernobyl_Nuclear_Power_Plant#...
https://en.wikipedia.org/wiki/Chernobyl_Nuclear_Power_Plant#...
They all had multiple serious incidents before and after the Chernobyl Disaster (1982 - partial core meltdown at #1, 1984 - incidents at #3 and #4, 1991 - fire at the turbine hall of #2). This was the most unsafe nuclear power plant in the whole USSR and the operators were in grave danger all the time.