I have only had these a couple of months, bought to go in a big bowl with others but there was no room so I put them together and this one flowered today.
One of the tremendously variable and confusing Echinopsis ; so many former independent genera have now been 'lumped' into the above it's almost imposible to ID many of the hybrids , of which yours may be one .
Thanks, @PaulB3 I guess these are all tissue culture grown by the million and specific labels aren't used except for 'succulent'.
Well I would have said Echinopsis, I have a couple remaining that look like that, night blooming and into the following day.