Word describing a distinct absence of intellectual curiosity?

I think "complacent" may be a close answer.

adj. having or showing a lack of interest or concern

Source: Merriam-Webster

(A correct answer would be based on how you describe this person. Does he/she know enough of the subject to not investigate or is the subject of discussion too bland for the person's taste so as to not arouse any interest? If the person is generally disinclined to new things, then perhaps "apathetic" or "numb" would make more sense, however, both these words lean more toward emotion than intellect.)

The term "philistine" applies to culture in general, which is not quite "intellectuality", as this latter substantive "intersects" with it.

(SOED) culture […] 6. A particular form, stage, or type of intellectual development or civilization in a society.

(OED) philistine adj. […] 2. Uneducated, unenlightened; indifferent or hostile to culture; aesthetically unsophisticated. (user LPH's bold and italic)

There is a specific term to name believers in the negativeness of intellectualism. (Wikipedia)

anti-intellectualism Hofstadter described anti-intellectualism as “resentment of the life of the mind, and those who are considered to represent it; and a disposition to constantly minimize the value of that life.

There is one problem with this term: you can't quite call those thinkers anti-intellectuals, would they so much as little refute intellectuality in a rational manner; strictly speaking, anti-intellectuals are intellectuals and the term is inherently a paradox: you do not criticize what you do not know.

Let's look now at the term "aintellectual", a term of recent origin that would come to mind naturally, but that few dictionaries include.

(Urban dictionary) absence or complete lack of intelligence

♦ The only word we could come up with to express the extent of the stupidity my niece's stepmother. "j is so ridiculously dumb, she is aintellectual!"

It seems that there is only a gradation of disinterest in intellectual matters, and in the extreme this comes down merely to complete dumbness. Apparently there is no single word counterpart of "philistine", not even an in-between, possibly because one of the important aspects of the essence of being man is intellect; is hardly a human being a human being without intellect, if that is conceivable.

How about sequacious?

Highly impressionable or unquestioning, especially in following a leader or embracing an idea:

False philosophers ... have beclouded educated but sequacious minds.

[American Heritage Dictionary]

Lexico gives

(of a person) lacking independence or originality of thought.

If you read anything without questioning it, then you are just part of the sequacious herd.

EDIT

I think @Brian Donovan has adverted to a nicety that had previously eluded me. I agree with him that sequacious isn't the proper word for the given description.

I therefore suggest meh, which the AHD defines as:

meh

1.Indifferent or apathetic:

I felt meh about going out, so I stayed in and watched a movie.

2. Unexceptional; so-so:

We thought the concert was meh and left early.

Blasé is another such word. AHD defines it as:

Unconcerned; nonchalant

had a blasé attitude about housecleaning.

I would describe such a person as dull. When used to describe a person it can have the following meanings:

[...]
4. Intellectually weak or obtuse; stupid.
5. Lacking responsiveness or alertness; insensitive: half-asleep and dull to the noises in the next room.
6. Dispirited; depressed: a dull mood.
[...]

(these are from the American Heritage Dictionary).

Note, these meanings are different from those when it is applied to an object - where it means the opposite of shiny - or an event - where it means boring.

Edited to add: A person who is dull (adjective) is also known as a dullard (noun):

A person regarded as mentally dull; a dolt.

This is again from the American Heritage Dictionary.

Maybe "apathetic" -

having or showing little or no interest, concern, or emotion

(From Merriam-Webster.)

Technically this is an opposite word, but it's somewhat diverged from being just the opposite of pathos.

I would most likely use the word vapid. M-W gives:

"lacking flavor, zest, interest, animation, or spirit : FLAT, DULL"

I find that in contemporary American use, the word (when a applied to a person) suggests that the person doesn't think too hard about anything.

In practice I often read "blase" for this. It's situational -- you're incurious about some particular thing, not in general. It's also more specific -- you're not curious because you've done it too many times. But in practice overwritten novels have things like "oh, we'll do this, and that, and ...", "relax," she said with a blase look, "it's a garden variety drug deal". Or "you seem pretty blase about this.", "It either works or it doesn't. Don't overthink it".

I think the word you're seeking is mumpsimus.

Without knowing more details about why the person might be "not intellectual curious", it's difficult to know what aspect to focus on. There are various 'not curious' and 'not intellectual' answers already given, as well as various 'not caring' situations.

But there's also the case where they're not simply apathetic but are actively hostile to intellect or curiosity. For example (definitions from the American Heritage Dictionary):

dogmatic:

2.a. Asserting or insisting upon ideas or principles, especially when unproven or unexamined, in an imperious or arrogant manner: "People in recovery groups can be dogmatic, asserting that the group's way is 'the way' or bashing other approaches" (Anne M. Fletcher).

b. Characterized by such assertion, often with an unconsidered rejection of criticism: a dogmatic adherence to a single educational model.

Or call the person a Luddite:

2. One who opposes technical or technological change.