An illiterate person is unable to read or write.
(in the US) Yes . . . and they do.
Illiterate
Illiterate
In third world countries, educational systems are poor and many citizens are illiterate. An illiterate person is one who can't read.
An illiterate person
If a person is illitrate he is a backward person not by his cast but by his studies
Illiterate is usually an adjective, and in this sense does not have a plural form. The noun for illiterate is illiteracy, for which the plural can be illiteracies, but it is awkward. Illiterate is sometimes used as a noun to describe an illiterate person, in which case the plural would be illiterates, e.g. as in the insult, "You are a bunch of illiterates!"
An illiterate person is unable to read or write at all, while a dyslexic person has difficulty with reading, spelling, or interpreting words, despite having normal intelligence. Dyslexia is a specific learning disability that affects reading and language processing skills, while illiteracy refers to the lack of basic reading and writing skills.
You call them illiterate.
Numerically challenged or mathematically challenged are terms used to describe someone who struggles with numbers and numerical concepts.
Probably, illiterate just means that the person cannot read. They can still talk which is crucial for language.