209968609 has 2 divisors, whose sum is σ = 209968610. Its totient is φ = 209968608.

The previous prime is 209968607. The next prime is 209968637. The reversal of 209968609 is 906869902.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 190854225 + 19114384 = 13815^2 + 4372^2 .

It is a cyclic number.

It is not a de Polignac number, because 209968609 - 2¹ = 209968607 is a prime.

Together with 209968607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (209968607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104984304 + 104984305.

It is an arithmetic number, because the mean of its divisors is an integer number (104984305).

Almost surely, 2^209968609 is an apocalyptic number.

It is an amenable number.

209968609 is a deficient number, since it is larger than the sum of its proper divisors (1).

209968609 is an equidigital number, since it uses as much as digits as its factorization.

209968609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 419904, while the sum is 49.

The square root of 209968609 is about 14490.2936133123. The cubic root of 209968609 is about 594.3625770300.

The spelling of 209968609 in words is "two hundred nine million, nine hundred sixty-eight thousand, six hundred nine".