4.2.5.2 Literal-Value Operands

For PIC32M devices, literal operands consist of just the literal value. For example:
  .align  2      # literal used with directive
  addiu   $sp,$sp,-8      # literal used with instruction
For PIC32C/SAM devices, literal operands for device instructions consists of the # character followed by the literal value. In directives, the operand consists of just the literal value.
  .align  1      @ literal used with directive
  sub     sp,sp,#12       @ literal used with instruction

In all cases, the value can be entered with any of the formats described in 4.3 Constants, provided that format is appropriate for the instruction or directive in which it is being used.