209906395217 has 4 divisors (see below), whose sum is σ = 209915717616. Its totient is φ = 209897072820.

The previous prime is 209906395123. The next prime is 209906395249. The reversal of 209906395217 is 712593609902.

209906395217 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209906395217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209906395277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4627343 + ... + 4672484.

It is an arithmetic number, because the mean of its divisors is an integer number (52478929404).

Almost surely, 2^209906395217 is an apocalyptic number.

It is an amenable number.

209906395217 is a deficient number, since it is larger than the sum of its proper divisors (9322399).

209906395217 is an equidigital number, since it uses as much as digits as its factorization.

209906395217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9322398.

The product of its (nonzero) digits is 1837080, while the sum is 53.

The spelling of 209906395217 in words is "two hundred nine billion, nine hundred six million, three hundred ninety-five thousand, two hundred seventeen".