Those things also stood out to me, fwiw.
Such children very often have difficulty relating well to peers because of the depth and narrowness of their range of interests-- that is, adults are more forgiving than other children are of a 3yo who ONLY wants to talk about, for example, washing machines. Adults might find it quirky but charming to have a child talk to them about model airplanes for an hour-- another four year old not-so-much, particularly if there isn't any give-and-take in terms of venturing to other topics.
You might do some reading about hyperlexic traits and maybe be sure to pay particular attention to some of those red-flag kinds of areas.
Prodigious verbal and visual memory, lack of play with "toys" or peers, preference for adults, need for order (in particular ways), sensory issues, potential motor concerns (though from the description, I wouldn't automatically say this was unusual), fascination with numbers and symbols, and very early literacy would all fit there. Some of those things are also quite common among gifted preschoolers-- but not all of them.
Some of them are also quite transient in some children-- real kids are way more than a set of bullet points, I'm aware, and no brief description on the internet is ever going to provide a full picture of who a child is.
