# 53 bit precision, rounding to nearest
C:\>perl -MMath::MPFR -le "print exp(Math::MPFR->new('15863.8668285308'))"
3.8888865970333893e6889

# 64 bit precision, rounding to nearest
C:\>perl -MMath::MPFR=":mpfr" -le "Rmpfr_set_default_prec(64);print exp(Math::MPFR->new('15863.8668285308'))"
3.88888659703546523928e6889

# 113 bit precision, rounding to nearest
C:\>perl -MMath::MPFR=":mpfr" -le "Rmpfr_set_default_prec(113);print exp(Math::MPFR->new('15863.8668285308'))"
3.88888659703546395686515111487812115e6889