780

780 is a natural number that follows 779 and precedes 781. It is the 39th triangular number, since 39 multiplied by 40 and divided by 2 equals 780. Its prime factorization is 2^2 × 3 × 5 × 13, making it a composite and non-square integer. The number has 24 positive divisors.

In various numeral systems, 780 can be represented as follows: in binary it is 1100001100, in hexadecimal it is 0x30C, and in Roman numerals it is written as DCCLXXX (500 + 200 + 50 + 30).

From a arithmetic perspective, the sum of all positive divisors of 780 (including itself) is 2352, so the sum of proper divisors is 1572. Because the sum of proper divisors exceeds 780, 780 is classified as an abundant number. It is also a Harshad (Niven) number in base 10, since it is divisible by the sum of its digits (7 + 8 + 0 = 15; 780 ÷ 15 = 52).

In popular usage, 780 appears as an area code in Canada, covering parts of Alberta, including the Edmonton region. The number also appears in various mathematical contexts as a representative example of a moderately sized composite, triangular number with a well-defined set of divisors.