Hello, I'm new to the forum and cactus.

[J0nblaze]

I just got this cactus I don't know what kind it is or why it's rotted.

[J0nblaze]

Here is a wider shot. I am going to transplant it of course. I was told I could cut off the bent part.

[Nino_G]

Hello and welcome to the forum
It looks like old Parodia leninghausii. It would help if you could make pictures under natural light, I can't see much on those posted above.

[J0nblaze]

Thanks, yeah the hps makes it funny. I'll move it for some serious pictures. I want to help it.

[Nino_G]

Is the lower part of the tallest stem soft/mushy? It doesn't look like rot to me, just corking of epidermis that comes with the old age. You can certainly cut the thick healthy-looking part and re-root it. There is multiple recent posts by Steve Johnson on how to do it in a proper and safe way.

Here is one thread that may help: https://www.cactiguide.com/forum/viewtopic.php?t=48117