209117609 has 6 divisors (see below), whose sum is σ = 209880174. Its totient is φ = 208357760.

The previous prime is 209117593. The next prime is 209117611. The reversal of 209117609 is 906711902.

It can be written as a sum of positive squares in 3 ways, for example, as 9517225 + 199600384 = 3085^2 + 14128^2 .

It is not a de Polignac number, because 209117609 - 2⁴ = 209117593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209117639) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 99449 + ... + 101529.

It is an arithmetic number, because the mean of its divisors is an integer number (34980029).

Almost surely, 2^209117609 is an apocalyptic number.

It is an amenable number.

209117609 is a deficient number, since it is larger than the sum of its proper divisors (762565).

209117609 is an frugal number, since it uses more digits than its factorization.

209117609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2715 (or 2398 counting only the distinct ones).

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 209117609 is about 14460.8993150495. The cubic root of 209117609 is about 593.5585085309.

The spelling of 209117609 in words is "two hundred nine million, one hundred seventeen thousand, six hundred nine".