Is Windows 2000 32 or 16-bit?

Could you please clarify for me if Windows 2000 is a 32-bit or 16-bit operating system? I'm curious to know the architecture that it's built on, as it's been a while since I last worked with that particular version of Windows. I understand that it's an older operating system, but I'm still interested in understanding its capabilities and limitations. Could you enlighten me on this point? Thank you in advance for your assistance.