218086861 has 2 divisors, whose sum is σ = 218086862. Its totient is φ = 218086860.

The previous prime is 218086823. The next prime is 218086871. The reversal of 218086861 is 168680812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114169225 + 103917636 = 10685^2 + 10194^2 .

It is a cyclic number.

It is not a de Polignac number, because 218086861 - 2¹¹ = 218084813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218086801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109043430 + 109043431.

It is an arithmetic number, because the mean of its divisors is an integer number (109043431).

Almost surely, 2^218086861 is an apocalyptic number.

It is an amenable number.

218086861 is a deficient number, since it is larger than the sum of its proper divisors (1).

218086861 is an equidigital number, since it uses as much as digits as its factorization.

218086861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36864, while the sum is 40.

The square root of 218086861 is about 14767.7642519103. The cubic root of 218086861 is about 601.9260890558.

The spelling of 218086861 in words is "two hundred eighteen million, eighty-six thousand, eight hundred sixty-one".