4391

4391 is a natural number that follows 4390 and precedes 4392. It is an odd integer.

4391 is a prime number; its only positive divisors are 1 and 4391. Because the square root of 4391 is about 66.3, a primality check by trial division up to 61 confirms there are no smaller divisors. As a result, 4391 has no nontrivial factorization into integers greater than 1.

In various representations, 4391 appears as decimal 4391; in binary it is 1000100100111; and in hexadecimal it is 0x1127. The sum of its decimal digits is 17. It is congruent to 3 modulo 4, so it cannot be expressed as a sum of two squares. It is not a perfect square and is not a triangular number, since the nearest triangular numbers are T93 = 4371 and T94 = 4465.

As a prime, 4391 shares properties typical of primes in number theory, such as serving as a basic example in primality testing and in discussions of modular arithmetic. Its status as a 4k+3 prime gives it the classical characteristic that it cannot be written as a sum of two integer squares.