218806543861 has 2 divisors, whose sum is σ = 218806543862. Its totient is φ = 218806543860.

The previous prime is 218806543849. The next prime is 218806543867. The reversal of 218806543861 is 168345608812.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 214340294961 + 4466248900 = 462969^2 + 66830^2 .

It is a cyclic number.

It is not a de Polignac number, because 218806543861 - 2¹¹ = 218806541813 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 218806543799 and 218806543808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218806543867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109403271930 + 109403271931.

It is an arithmetic number, because the mean of its divisors is an integer number (109403271931).

Almost surely, 2^218806543861 is an apocalyptic number.

It is an amenable number.

218806543861 is a deficient number, since it is larger than the sum of its proper divisors (1).

218806543861 is an equidigital number, since it uses as much as digits as its factorization.

218806543861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2211840, while the sum is 52.

The spelling of 218806543861 in words is "two hundred eighteen billion, eight hundred six million, five hundred forty-three thousand, eight hundred sixty-one".