206409 has 8 divisors (see below), whose sum is σ = 314560. Its totient is φ = 117936.

The previous prime is 206407. The next prime is 206411. The reversal of 206409 is 904602.

It is an interprime number because it is at equal distance from previous prime (206407) and next prime (206411).

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

It is not a de Polignac number, because 206409 - 2¹ = 206407 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 9829 = 206409 / (2 + 0 + 6 + 4 + 0 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206407) 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, 4894 + ... + 4935.

It is an arithmetic number, because the mean of its divisors is an integer number (39320).

2²⁰⁶⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

206409 is a deficient number, since it is larger than the sum of its proper divisors (108151).

206409 is an equidigital number, since it uses as much as digits as its factorization.

206409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9839.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 206409 is about 454.3225726287. The cubic root of 206409 is about 59.0984662381.

The spelling of 206409 in words is "two hundred six thousand, four hundred nine".