209811996854717 has 2 divisors, whose sum is σ = 209811996854718. Its totient is φ = 209811996854716.

The previous prime is 209811996854687. The next prime is 209811996854767. The reversal of 209811996854717 is 717458699118902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 200628272677561 + 9183724177156 = 14164331^2 + 3030466^2 .

It is a cyclic number.

It is not a de Polignac number, because 209811996854717 - 2⁸ = 209811996854461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209811996854767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104905998427358 + 104905998427359.

It is an arithmetic number, because the mean of its divisors is an integer number (104905998427359).

Almost surely, 2^{209811996854717} is an apocalyptic number.

It is an amenable number.

209811996854717 is a deficient number, since it is larger than the sum of its proper divisors (1).

209811996854717 is an equidigital number, since it uses as much as digits as its factorization.

209811996854717 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 548674560, while the sum is 77.

The spelling of 209811996854717 in words is "two hundred nine trillion, eight hundred eleven billion, nine hundred ninety-six million, eight hundred fifty-four thousand, seven hundred seventeen".