129999209 has 2 divisors, whose sum is σ = 129999210. Its totient is φ = 129999208.

The previous prime is 129999179. The next prime is 129999217. The reversal of 129999209 is 902999921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127057984 + 2941225 = 11272^2 + 1715^2 .

It is a cyclic number.

It is not a de Polignac number, because 129999209 - 2¹⁶ = 129933673 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (129999269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64999604 + 64999605.

It is an arithmetic number, because the mean of its divisors is an integer number (64999605).

Almost surely, 2^129999209 is an apocalyptic number.

It is an amenable number.

129999209 is a deficient number, since it is larger than the sum of its proper divisors (1).

129999209 is an equidigital number, since it uses as much as digits as its factorization.

129999209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 236196, while the sum is 50.

The square root of 129999209 is about 11401.7195632940. The cubic root of 129999209 is about 506.5786744605.

The spelling of 129999209 in words is "one hundred twenty-nine million, nine hundred ninety-nine thousand, two hundred nine".