I can't demo at trycf.com because apparently PrecisionEvaluate() is disallowed. But there's a difference even when removing precision evaluate - Lucee spits back a rounded number, whereas ACF kicks out a number in scientific notation.

the question - shouldn't these two app servers at least agree on how numbers are handled, since both ride atop Java, and there's no good reason for them not to?

And shouldn't PrecisionEvaluate() handle this large integer the same either way?

somewhat answering my own question... details in https://rorylaitila.gitbooks.io/lucee/content/numeric.html. Still, frustrating that the two cf engines behave so differently in the area of math