Serendipity35

In 1999, Google's servers were ten CPUs across four servers. 

Google doesn’t publicly disclose the exact number of servers it operates, but estimates suggest it’s in the millions.  A 2011 analysis based on Google’s energy usage suggested around 900,000 servers, but that was over a decade ago. In 2016, Gartner estimated Google had around 2.5 million servers globally. Google has designed systems like Spanner to manage fleets ranging from 1 million to 10 million machines, hinting at massive infrastructure growth. Given the scale of Google’s services—Search, YouTube, Gmail, Cloud, and AI—it’s reasonable to assume the number is well above 2.5 million today, spread across dozens of data centers worldwide.

Other tech giants like Amazon and Microsoft don't publish exact server counts, so these are educated estimations. 

Amazon (AWS) probably has ~4–5 million  as the largest cloud provider globally with a massive scale across 100+ data centers.

Google probably has ~2.5–3 million+ for its heavy investment in AI and search, and is expanding rapidly with Gemini and Cloud.

Microsoft (Azure) is close with ~2–3 million+ but has a strong enterprise presence and is growing with Office 365, Copilot, and Azure AI.