I think that meyranii is not a bad match for your plant. I had been thinking about forms of M. haageana, but the flower didn't look right and it seems to be growing more columnar than haageana does. This suggests meyranii for sure, though the description of meyranii says the radial spines are yellow, tipped brown when young, and your plant has radial spines that look all white. Maybe it is more variable than the description suggests.
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Chris43, moderator