Pi is just our name for the ratio of a circle's circumference to its diameter regardless of the base.

This is why it doesn't make sense for an intelligent species not to know what 'pi' is. It's an important concept that pops up immediately in basic geometry and just keeps popping up over and over all the way to general relativity and beyond.

Yes, an intelligent species may not know pi but they would not have progressed even to the point of basic geometry in the maths and sciences.