208639655209 has 2 divisors, whose sum is σ = 208639655210. Its totient is φ = 208639655208.

The previous prime is 208639655197. The next prime is 208639655243. The reversal of 208639655209 is 902556936802.

It is a happy number.

208639655209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 172829769984 + 35809885225 = 415728^2 + 189235^2 .

It is a cyclic number.

It is not a de Polignac number, because 208639655209 - 2¹³ = 208639647017 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 208639655209.

It is not a weakly prime, because it can be changed into another prime (208639655509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104319827604 + 104319827605.

It is an arithmetic number, because the mean of its divisors is an integer number (104319827605).

Almost surely, 2^208639655209 is an apocalyptic number.

It is an amenable number.

208639655209 is a deficient number, since it is larger than the sum of its proper divisors (1).

208639655209 is an equidigital number, since it uses as much as digits as its factorization.

208639655209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6998400, while the sum is 55.

The spelling of 208639655209 in words is "two hundred eight billion, six hundred thirty-nine million, six hundred fifty-five thousand, two hundred nine".