6391 has 8 divisors (see below), whose sum is σ = 8064. Its totient is φ = 4920.

The previous prime is 6389. The next prime is 6397. The reversal of 6391 is 1936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6391 - 2¹ = 6389 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6397) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36 + ... + 118.

It is an arithmetic number, because the mean of its divisors is an integer number (1008).

2⁶³⁹¹ is an apocalyptic number.

6391 is a deficient number, since it is larger than the sum of its proper divisors (1673).

6391 is a wasteful number, since it uses less digits than its factorization.

6391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101.

The product of its digits is 162, while the sum is 19.

The square root of 6391 is about 79.9437302107. The cubic root of 6391 is about 18.5576482727.

It can be divided in two parts, 6 and 391, that multiplied together give a triangular number (2346 = T₆₈).

The spelling of 6391 in words is "six thousand, three hundred ninety-one".