209485709 has 2 divisors, whose sum is σ = 209485710. Its totient is φ = 209485708.

The previous prime is 209485667. The next prime is 209485753. The reversal of 209485709 is 907584902.

It is a happy number.

It is an a-pointer prime, because the next prime (209485753) can be obtained adding 209485709 to its sum of digits (44).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 167624809 + 41860900 = 12947^2 + 6470^2 .

It is a cyclic number.

It is not a de Polignac number, because 209485709 - 2¹⁶ = 209420173 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 209485709.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209485799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104742854 + 104742855.

It is an arithmetic number, because the mean of its divisors is an integer number (104742855).

Almost surely, 2^209485709 is an apocalyptic number.

It is an amenable number.

209485709 is a deficient number, since it is larger than the sum of its proper divisors (1).

209485709 is an equidigital number, since it uses as much as digits as its factorization.

209485709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 181440, while the sum is 44.

The square root of 209485709 is about 14473.6211433076. The cubic root of 209485709 is about 593.9065755264.

The spelling of 209485709 in words is "two hundred nine million, four hundred eighty-five thousand, seven hundred nine".