1784

1784 = 2³ x 223.

1784 is a deficient number because the sum of its proper divisors (1 + 2 + 4 + 8 + 223 + 446 + 892 = 1576) is less than the number i! tself.

1784 is a year in which the month of February has five Sundays.

1784 is a number n such that n² + 1 and n² + 3 are both prime: 3,182,657 and 3,182,659.

1784 is a composite number such that exactly eight distinct permutations of its digits give primes: 1487, 1847, 4817, 4871, 7481, 7841, 8147, and 8741.


The U.S. Congress ratified the Treaty of Paris on Jan. 14, 1784, officially ending the Revolutionary War.

Source: The Positive Integers

Prime and composite numbers