Is it correct to say that (for instance) 14690 and 41906 are anagrams, or does that term only apply to words? What is the correct term?

An anagram is a type of word play, the result of rearranging the letters of a word or phrase to produce a new word or phrase, using all the original letters exactly once; e.g., orchestra = carthorse, A decimal point = I'm a dot in place. Someone who creates anagrams is called an anagrammatist. The original word or phrase is known as the subject of the anagram.

https://en.wikipedia.org/wiki/Anagram

As far a numbers -- I believe it should be qualified as a "numeric anagram." Example: Although the date of the event appears to be two years too early, it is important to remember that Nostradamus often wrote in anagrams. The real clue is that the date 1999 is nothing more than a numeric anagram. If we reverse the order of the “1”s and “9”s, we arrive at the date 9-11-1 (the date of the 9-11 attacks).

nostradamus101.com/prophecies/part3 webpage no longer exists