211817009 has 2 divisors, whose sum is σ = 211817010. Its totient is φ = 211817008.

The previous prime is 211816999. The next prime is 211817027. The reversal of 211817009 is 900718112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 151413025 + 60403984 = 12305^2 + 7772^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-211817009 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (211817509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105908504 + 105908505.

It is an arithmetic number, because the mean of its divisors is an integer number (105908505).

Almost surely, 2^211817009 is an apocalyptic number.

It is an amenable number.

211817009 is a deficient number, since it is larger than the sum of its proper divisors (1).

211817009 is an equidigital number, since it uses as much as digits as its factorization.

211817009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 29.

The square root of 211817009 is about 14553.9344852174. The cubic root of 211817009 is about 596.1015856525.

The spelling of 211817009 in words is "two hundred eleven million, eight hundred seventeen thousand, nine".