1 The total number or quantity; aggregate; the quantity at hand or under consideration
2. The whole effect, significance, or import
3. A principal sum and the interest on it'usage Number is regularly used with count nouns while amount is mainly used with mass nouns. The use of amount with count nouns has been frequently criticized; it usually occurs when the number of things is thought of as a mass or collection or when money is involved
How much of something is available

To be tantamount or equivalent to.