21 Inc.

21 Inc. (historical company; formerly 21e6, later 21 Inc.)

21 Inc. was a U.S.-based Bitcoin startup founded in 2013 that initially focused on bitcoin mining (including industrial mining efforts) and later experimented with Bitcoin-enabled hardware and developer products (notably the “21 Bitcoin Computer” era). (coindesk.com)

Pivot and acquisition

By 2017–2018, the company de-emphasized mining and pivoted toward a micropayments-driven product that became Earn.com (a “paid email / paid tasks” concept). In April 2018, Coinbase acquired Earn.com (the renamed 21 Inc.). (coindesk.com)

What https://21.co refers to today (different entity / brand)

The domain 21.co is currently associated with 21.co (the Swiss “21.co group”), known publicly as the parent company of 21Shares (a crypto ETP issuer) and a technology arm that builds institutional/on-chain products (including wrapped tokens and related infrastructure). (coindesk.com)

On its site, 21.co describes wrapped tokens intended to provide cross-chain liquidity with institutional/custodial controls (i.e., a centralized custodial wrapping model rather than a mining/validation role). (21.co)

Miner–validator category: how it fits (and how it doesn’t)

• Fits (historically): 21 Inc. began life as a bitcoin mining company. (coindesk.com)
• Does not fit (current 21.co site): today’s 21.co is primarily an investment-products / on-chain tokenization & wrapped-token organization, not a Bitcoin miner or a proof-of-stake validator operator as its headline business. (coindesk.com)

Naming note: “21 Inc.” (the 2013 startup that became Earn.com) and the present-day 21.co group are commonly conflated because of the shared “21” branding and domain reuse, but they refer to different corporate histories. (coindesk.com)