205689217 has 4 divisors (see below), whose sum is σ = 206272260. Its totient is φ = 205106176.

The previous prime is 205689191. The next prime is 205689241. The reversal of 205689217 is 712986502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 712986502 = 2 ⋅356493251.

It can be written as a sum of positive squares in 2 ways, for example, as 63984001 + 141705216 = 7999^2 + 11904^2 .

It is a cyclic number.

It is not a de Polignac number, because 205689217 - 2⁷ = 205689089 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 205689217.

It is not an unprimeable number, because it can be changed into a prime (205689017) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 290992 + ... + 291697.

It is an arithmetic number, because the mean of its divisors is an integer number (51568065).

Almost surely, 2^205689217 is an apocalyptic number.

It is an amenable number.

205689217 is a deficient number, since it is larger than the sum of its proper divisors (583043).

205689217 is an equidigital number, since it uses as much as digits as its factorization.

205689217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583042.

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 205689217 is about 14341.8693690885. The cubic root of 205689217 is about 590.2969079198.

The spelling of 205689217 in words is "two hundred five million, six hundred eighty-nine thousand, two hundred seventeen".