209149439 has 2 divisors, whose sum is σ = 209149440. Its totient is φ = 209149438.

The previous prime is 209149429. The next prime is 209149441. The reversal of 209149439 is 934941902.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209149439 is a prime.

It is a Sophie Germain prime.

Together with 209149441, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 209149396 and 209149405.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209149429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104574719 + 104574720.

It is an arithmetic number, because the mean of its divisors is an integer number (104574720).

Almost surely, 2^209149439 is an apocalyptic number.

209149439 is a deficient number, since it is larger than the sum of its proper divisors (1).

209149439 is an equidigital number, since it uses as much as digits as its factorization.

209149439 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69984, while the sum is 41.

The square root of 209149439 is about 14461.9998271332. Note that the first 3 decimals coincide. The cubic root of 209149439 is about 593.5886223808.

The spelling of 209149439 in words is "two hundred nine million, one hundred forty-nine thousand, four hundred thirty-nine".