209086681 has 2 divisors, whose sum is σ = 209086682. Its totient is φ = 209086680.

The previous prime is 209086663. The next prime is 209086727. The reversal of 209086681 is 186680902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 207821056 + 1265625 = 14416^2 + 1125^2 .

It is a cyclic number.

It is not a de Polignac number, because 209086681 - 2¹¹ = 209084633 is a prime.

It is a super-2 number, since 2×209086681² = 87434480343191522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209086651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104543340 + 104543341.

It is an arithmetic number, because the mean of its divisors is an integer number (104543341).

Almost surely, 2^209086681 is an apocalyptic number.

It is an amenable number.

209086681 is a deficient number, since it is larger than the sum of its proper divisors (1).

209086681 is an equidigital number, since it uses as much as digits as its factorization.

209086681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 209086681 is about 14459.8299090964. The cubic root of 209086681 is about 593.5292451215.

The spelling of 209086681 in words is "two hundred nine million, eighty-six thousand, six hundred eighty-one".