$ perl -MDevel::Peek -le '$i=8_000_000_000; print Dump($i); \
      print ~~$i; print Dump($i)'

SV = NV(0x8175f88) at 0x8170fe8
  REFCNT = 1
  FLAGS = (NOK,pNOK)
  NV = 8000000000

4294967295
SV = PVNV(0x818d040) at 0x8170fe8
  REFCNT = 1
  FLAGS = (NOK,pIOK,pNOK,IsUV)
  UV = 4294967295
  NV = 8000000000
  PV = 0