3665

3665 is a natural number that comes after 3664 and before 3666. In mathematics, it is an odd composite number. Its prime factorization is 5 × 733, making it a semiprime. Both factors are primes; 733 is itself a prime. The number is congruent to 1 modulo 4, and by Fermat's two-squares theorem it can be expressed as a sum of two squares. One such representation is 3665 = 23^2 + 56^2, since 23^2=529 and 56^2=3136, totaling 3665. In binary, 3665 is 111001010001_2. It is divisible by 5 as indicated by its last digit in base 10; 3665 = 5 × 733. In Roman numerals, it is written MMMDCLXV. The sum of its decimal digits is 3+6+6+5 = 20, giving a digital root of 2. The proper divisors are 1, 5, and 733; their sum is 739, so 3665 is a deficient number (sum of divisors less than the number). 3665 is not a square, cube, or triangular number. In recreational and number theory contexts, semiprimes of this form are used as examples illustrating factorization properties and sums of squares representations.