A number that shares its prime factors with another.

(number theory) A (nonzero) natural number that is expressible as the product of two (or more) natural numbers other than itself and 1.

(idiomatic, chiefly US, politics) Of unpopular status, particularly of politicians.

Dated form of possession is nine-tenths of the law.

One who has possession of a thing has some right to it; a popular statement of the doctrine of adverse possession.

(physics) A quantum number related to the difference between the numbers of quarks and antiquarks in a system of subatomic particles

(number theory) Any of a series of numbers formed from the sum of the reciprocals of consecutive natural numbers

(mathematics) A number whose decimal representation of its square ends in itself.

(number theory) One of a pair of numbers having the property that the sum of the divisors of each, excluding itself, is equal to the other number.

(physics) The number of neutrons in the nucleus of an atom or isotope. Symbol: N