For some reason, using parseInt or parseFloat on NumberLong gives NaN, but using arithmetic operations converts them to ints/floats without issues?

See the following:

> parseInt(NumberLong(2))
NaN
> parseFloat(NumberLong(2))
NaN
> NumberLong(2) + NumberLong(0)
2 <-- this is an int, not NumberLong

So this obviously works:

> parseInt(NumberLong(2) + NumberLong(0))
2

Tested on Mongo 2.4.9 and 2.6.3. This seems like a completely illogical behaviour. This became important since PHP driver converts every number to NumberFloat.