3609

3609 is a natural number that follows 3608 and precedes 3610. In mathematics, it is an odd composite integer with the prime factorization 3² × 401. Because the sum of its decimal digits is 3 + 6 + 0 + 9 = 18, and 3609 divided by 18 equals 200.5, the number is not a Harshad number in base ten; however, it is divisible by the sum of its digits in base nine, where the digit sum is 4 + 0 + 0 (in base‑9 representation 504₉). The integer is also divisible by nine, since 3 + 6 + 0 + 9 = 18 and 18 is a multiple of nine, giving 3609 ÷ 9 = 401. In Roman numerals the value is expressed as MMMDCIX (3000 + 600 + 9).

Beyond its purely numerical properties, 3609 appears as an identifier in a few catalogues. Asteroid 3609, discovered in 1983, is a main‑belt object designated 1983 VN and named “Baker” after the American astronomer James Baker. The number is also used as a model or part number in engineering contexts, such as the Siemens SIMATIC S7‑300 series controller model 3609, and as a postal code segment in certain countries, though it does not correspond to a unique geographic area worldwide. The term “3609” therefore primarily denotes the integer itself and occasionally serves as an identifier in scientific and industrial naming systems.