209630787217 has 2 divisors, whose sum is σ = 209630787218. Its totient is φ = 209630787216.

The previous prime is 209630787181. The next prime is 209630787221. The reversal of 209630787217 is 712787036902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 119765137041 + 89865650176 = 346071^2 + 299776^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209630787217 is a prime.

It is not a weakly prime, because it can be changed into another prime (209630787287) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104815393608 + 104815393609.

It is an arithmetic number, because the mean of its divisors is an integer number (104815393609).

Almost surely, 2^209630787217 is an apocalyptic number.

It is an amenable number.

209630787217 is a deficient number, since it is larger than the sum of its proper divisors (1).

209630787217 is an equidigital number, since it uses as much as digits as its factorization.

209630787217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1778112, while the sum is 52.

The spelling of 209630787217 in words is "two hundred nine billion, six hundred thirty million, seven hundred eighty-seven thousand, two hundred seventeen".