Setting Binary Value in PHP?

Is there a way to set a binary value in PHP similar to the way you can set a variable in Hex or Octal?

Binary: $var = ???
Octal: $var = 0777777777777
Decimal: $var = -1
Hex: $var = 0xFFFFFF

I was thinking 0b11111111111111111111111111111111 but that didn’t work.