4389

4389 is a natural number that comes after 4388 and before 4390. In mathematics, it is a composite number with prime factorization 3 × 7 × 11 × 19, making it square-free and a four-prime product (often described as a 4-almost prime).

As a result of its prime factorization, 4389 has 16 positive divisors, all formed by multiplying any subset of the primes {3, 7, 11, 19}. The sum of its divisors is 7680. Its Euler totient, φ(4389), equals 2160, which counts the positive integers up to 4389 that are relatively prime to it.

The number is divisible by each of its prime factors: 3, 7, 11, and 19. Consequently, it is divisible by 3 (and by 21, 33, 57, and other combinations), but it is not divisible by 9 since the sum of its digits is 24, which is not a multiple of 9.

In representations other than decimal, 4389 equals 0x1125 in hexadecimal, and its binary form is 1000100100100101. This makes it a convenient example in discussions of prime-factorization, divisor counts, and basic base conversions.

Overall, 4389 is notable chiefly as an example of a square-free number that is the product of four distinct primes, illustrating several standard arithmetic properties of composite numbers.