julia> π^Int(-1)
ERROR: DomainError with -1:
Cannot raise an integer x to a negative power -1.
Convert input to float.
Stacktrace:
 [1] throw_domerr_powbysq(::Float64, p::Int64)
   @ Base ./intfuncs.jl:302
 [2] power_by_squaring(x_::Irrational{:π}, p::Int64; mul::typeof(*))
   @ Base ./intfuncs.jl:327
 [3] power_by_squaring
   @ ./intfuncs.jl:316 [inlined]
 [4] ^(x::Irrational{:π}, p::Int64)
   @ Base ./intfuncs.jl:352
 [5] top-level scope
   @ REPL[1]:1

julia> isinteger(π)
false