Is it safe to treat entity IDs as hexadecimal numbers ?

[tothewine]

And most importantly... while it seems to be the case for my example test below, are they guaranteed to be sequential everywhere?

hexdec('5bdc8e46653e355b1') = 1.059091517652E+20
 hexdec('5bdc95aa8c0b1223e') = 1.0590928179287E+20 is MORE than previous line.
 hexdec('5bdd78d29c3027bbd') = 1.0591327797221E+20 is MORE than previous line.
 hexdec('5bdd7cffd629d49c5') = 1.059133514489E+20 is MORE than previous line.
 hexdec('5bdd7d3edff4b010f') = 1.0591335578085E+20 is MORE than previous line. 

Also, is it possible to use where clause on the id like this?

  $results = $manager->getrepository('Lead')->where(['id>='=>'5a1c4b6a6c66a5fa9'])->find();