8391 has 4 divisors (see below), whose sum is σ = 11192. Its totient is φ = 5592.

The previous prime is 8389. The next prime is 8419. The reversal of 8391 is 1938.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 8391 - 2¹ = 8389 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1396 + ... + 1401.

It is an arithmetic number, because the mean of its divisors is an integer number (2798).

2⁸³⁹¹ is an apocalyptic number.

8391 is a deficient number, since it is larger than the sum of its proper divisors (2801).

8391 is a wasteful number, since it uses less digits than its factorization.

8391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2800.

The product of its digits is 216, while the sum is 21.

The square root of 8391 is about 91.6024017152. The cubic root of 8391 is about 20.3206645679.

The spelling of 8391 in words is "eight thousand, three hundred ninety-one".