any number of

any number of

A large, non-specific amount of something. You can talk to any number of doctors, but they will all give you the same prognosis.
See also: any, number, of
Farlex Dictionary of Idioms.

any number of someone or something

Fig. a large number; a sufficiently large number. (Used when the exact number is not important.) Any number of people can vouch for my honesty. I can give you any number of reasons why I should join the army. I ate at that diner any number of times and never became ill.
See also: any, number, of
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

any number of

Many; also, no particular amount of. The meaning here depends on the context. I can give you any number of reasons for John's absence means I can offer many reasons. Any number of subscribers might stay home means that an unknown number will not attend.
See also: any, number, of
The American Heritage® Dictionary of Idioms by Christine Ammer.

any number of

If you say there are any number of things or people, you mean that there is a large number of those things or people. I'm sure there are any number of young ladies here who would be delighted to keep you company. I'm expecting to be here for several days, and there are any number of things I'd like you to show me.
See also: any, number, of
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • so many
  • so much/many
  • a few
  • do a number on, to
  • number of things or people
  • a number of
  • a number of (something)
  • round up to (something)
  • number off
  • digit