208691 has 6 divisors (see below), whose sum is σ = 242820. Its totient is φ = 178836.

The previous prime is 208687. The next prime is 208697. The reversal of 208691 is 196802.

It is not a de Polignac number, because 208691 - 2² = 208687 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 208691.

It is not an unprimeable number, because it can be changed into a prime (208697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2081 + ... + 2178.

It is an arithmetic number, because the mean of its divisors is an integer number (40470).

2²⁰⁸⁶⁹¹ is an apocalyptic number.

208691 is a deficient number, since it is larger than the sum of its proper divisors (34129).

208691 is an equidigital number, since it uses as much as digits as its factorization.

208691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4273 (or 4266 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 208691 is about 456.8271007723. The cubic root of 208691 is about 59.3154605372.

The spelling of 208691 in words is "two hundred eight thousand, six hundred ninety-one".