(number theory) A deficient number.

(number theory) A number that is greater than the sum of all of its divisors except itself.

(mathematics) The limit of a convergent sequence of rational numbers, whether the limit is a rational number such as 2, -5, or 2/7 or whether the limit is an irrational number such as the square root of two or the circumference of the circle whose radius is one.

(number theory) A number that is the sum of all of its divisors except itself.

(complex analysis, strict sense) A number of the form bi, where b is any real number and i denotes the imaginary unit.

The sequence of digits used to identify a particular destination telephone in a network. / (in the plural, humorous) A large number.

(colloquial) A telephone number.

A number used as an adjective; either a cardinal adjective (such as one) or an ordinal adjective (such as third)

(mathematics) An integer / (mathematics) A natural number (positive or non-negative integer)

(mathematics) Of or relating to number theory.