209999999999989 has 2 divisors, whose sum is σ = 209999999999990. Its totient is φ = 209999999999988.

The previous prime is 209999999999981. The next prime is 210000000000023. The reversal of 209999999999989 is 989999999999902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 209878239480625 + 121760519364 = 14487175^2 + 348942^2 .

It is a cyclic number.

It is not a de Polignac number, because 209999999999989 - 2³ = 209999999999981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209999999999981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104999999999994 + 104999999999995.

It is an arithmetic number, because the mean of its divisors is an integer number (104999999999995).

Almost surely, 2^{209999999999989} is an apocalyptic number.

It is an amenable number.

209999999999989 is a deficient number, since it is larger than the sum of its proper divisors (1).

209999999999989 is an equidigital number, since it uses as much as digits as its factorization.

209999999999989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4518872583696, while the sum is 118.

The spelling of 209999999999989 in words is "two hundred nine trillion, nine hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred eighty-nine".