208391 has 2 divisors, whose sum is σ = 208392. Its totient is φ = 208390.

The previous prime is 208387. The next prime is 208393. The reversal of 208391 is 193802.

208391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 208391 - 2² = 208387 is a prime.

Together with 208393, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104195 + 104196.

It is an arithmetic number, because the mean of its divisors is an integer number (104196).

2²⁰⁸³⁹¹ is an apocalyptic number.

208391 is a deficient number, since it is larger than the sum of its proper divisors (1).

208391 is an equidigital number, since it uses as much as digits as its factorization.

208391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 208391 is about 456.4986308851. The cubic root of 208391 is about 59.2870242817.

The spelling of 208391 in words is "two hundred eight thousand, three hundred ninety-one".