208978680217 has 2 divisors, whose sum is σ = 208978680218. Its totient is φ = 208978680216.

The previous prime is 208978680199. The next prime is 208978680227. The reversal of 208978680217 is 712086879802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 124965078016 + 84013602201 = 353504^2 + 289851^2 .

It is a cyclic number.

It is not a de Polignac number, because 208978680217 - 2¹¹ = 208978678169 is a prime.

It is a super-3 number, since 3×208978680217³ (a number of 35 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (208978680227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104489340108 + 104489340109.

It is an arithmetic number, because the mean of its divisors is an integer number (104489340109).

Almost surely, 2^208978680217 is an apocalyptic number.

It is an amenable number.

208978680217 is a deficient number, since it is larger than the sum of its proper divisors (1).

208978680217 is an equidigital number, since it uses as much as digits as its factorization.

208978680217 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5419008, while the sum is 58.

The spelling of 208978680217 in words is "two hundred eight billion, nine hundred seventy-eight million, six hundred eighty thousand, two hundred seventeen".