Rounding gives incorrect result for large numbers

[umnikos]

As of version 1.5.8 it seems the largest result that the round function returns is 18446744073709551616 (aka. 2^64) and if the input is larger than that it just returns 18446744073709551616 instead. This applies to floor and ceil as well.

Example:

> a=50!/e
approx. 11188719610782480506113237301990711351094883421697948286614915791.4883462282
> round(a)
approx. 18446744073709551616
# expected result is 11188719610782480506113237301990711351094883421697948286614915791