integral to floating point conversion

[Andrei Alexandrescu via Digitalmars-d]

On 7/2/16 4:30 PM, Walter Bright wrote:
> On 7/2/2016 1:17 PM, Andrei Alexandrescu wrote:
>> So what's the fastest way to figure that an integral is convertible to a
>> floating point value precisely (i.e. no other integral converts to the
>> same
>> floating point value)? Thanks! -- Andrei
>
> Test that its absolute value is <= the largest unsigned value
> represented by the float's mantissa bits.

What is the largest unsigned value represented by the float's mantissa 
bits? I recall there is a constant somewhere for it. -- Andrei