206391 has 8 divisors (see below), whose sum is σ = 278640. Its totient is φ = 135872.

The previous prime is 206383. The next prime is 206399. The reversal of 206391 is 193602.

It is an interprime number because it is at equal distance from previous prime (206383) and next prime (206399).

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 206391 - 2³ = 206383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206399) 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, 120 + ... + 653.

It is an arithmetic number, because the mean of its divisors is an integer number (34830).

2²⁰⁶³⁹¹ is an apocalyptic number.

206391 is a deficient number, since it is larger than the sum of its proper divisors (72249).

206391 is an equidigital number, since it uses as much as digits as its factorization.

206391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 865.

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 206391 is about 454.3027624833. The cubic root of 206391 is about 59.0967482844.

Adding to 206391 its reverse (193602), we get a palindrome (399993).

The spelling of 206391 in words is "two hundred six thousand, three hundred ninety-one".