208680821 has 2 divisors, whose sum is σ = 208680822. Its totient is φ = 208680820.

The previous prime is 208680803. The next prime is 208680833. The reversal of 208680821 is 128086802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 186459025 + 22221796 = 13655^2 + 4714^2 .

It is a cyclic number.

It is not a de Polignac number, because 208680821 - 2¹⁰ = 208679797 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208680421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104340410 + 104340411.

It is an arithmetic number, because the mean of its divisors is an integer number (104340411).

Almost surely, 2^208680821 is an apocalyptic number.

It is an amenable number.

208680821 is a deficient number, since it is larger than the sum of its proper divisors (1).

208680821 is an equidigital number, since it uses as much as digits as its factorization.

208680821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12288, while the sum is 35.

The square root of 208680821 is about 14445.7890404090. The cubic root of 208680821 is about 593.1449614183.

The spelling of 208680821 in words is "two hundred eight million, six hundred eighty thousand, eight hundred twenty-one".