208668980809 has 9 divisors (see below), whose sum is σ = 218146988199. Its totient is φ = 199586366760.

The previous prime is 208668980801. The next prime is 208668980843. The reversal of 208668980809 is 908089866802.

The square root of 208668980809 is 456803.

It is a perfect power (a square), and thus also a powerful number.

208668980809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 2534820409 + 206134160400 = 50347^2 + 454020^2 .

It is not a de Polignac number, because 208668980809 - 2³ = 208668980801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (208668980801) 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 in 8 ways as a sum of consecutive naturals, for example, 10496539 + ... + 10516399.

Almost surely, 2^208668980809 is an apocalyptic number.

208668980809 is the 456803-rd square number.

208668980809 is the 228402-nd centered octagonal number.

It is an amenable number.

208668980809 is a deficient number, since it is larger than the sum of its proper divisors (9478007390).

208668980809 is an frugal number, since it uses more digits than its factorization.

208668980809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39768 (or 19884 counting only the distinct ones).

The product of its (nonzero) digits is 23887872, while the sum is 64.

Multiplying 208668980809 by its sum of digits (64), we get a square (13354814771776 = 3654424²).

The spelling of 208668980809 in words is "two hundred eight billion, six hundred sixty-eight million, nine hundred eighty thousand, eight hundred nine".