208816981 has 2 divisors, whose sum is σ = 208816982. Its totient is φ = 208816980.

The previous prime is 208816943. The next prime is 208816991. The reversal of 208816981 is 189618802.

208816981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 207100881 + 1716100 = 14391^2 + 1310^2 .

It is a cyclic number.

It is not a de Polignac number, because 208816981 - 2²⁷ = 74599253 is a prime.

It is a super-2 number, since 2×208816981² = 87209063107908722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208816921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104408490 + 104408491.

It is an arithmetic number, because the mean of its divisors is an integer number (104408491).

Almost surely, 2^208816981 is an apocalyptic number.

It is an amenable number.

208816981 is a deficient number, since it is larger than the sum of its proper divisors (1).

208816981 is an equidigital number, since it uses as much as digits as its factorization.

208816981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 55296, while the sum is 43.

The square root of 208816981 is about 14450.5010639770. The cubic root of 208816981 is about 593.2739383868.

The spelling of 208816981 in words is "two hundred eight million, eight hundred sixteen thousand, nine hundred eighty-one".