208209202681 has 2 divisors, whose sum is σ = 208209202682. Its totient is φ = 208209202680.

The previous prime is 208209202543. The next prime is 208209202699. The reversal of 208209202681 is 186202902802.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 105565858281 + 102643344400 = 324909^2 + 320380^2 .

It is a cyclic number.

It is not a de Polignac number, because 208209202681 - 2¹⁵ = 208209169913 is a prime.

It is a super-2 number, since 2×208209202681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (208209202181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104104601340 + 104104601341.

It is an arithmetic number, because the mean of its divisors is an integer number (104104601341).

Almost surely, 2^208209202681 is an apocalyptic number.

It is an amenable number.

208209202681 is a deficient number, since it is larger than the sum of its proper divisors (1).

208209202681 is an equidigital number, since it uses as much as digits as its factorization.

208209202681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 55296, while the sum is 40.

The spelling of 208209202681 in words is "two hundred eight billion, two hundred nine million, two hundred two thousand, six hundred eighty-one".