218516835221 has 2 divisors, whose sum is σ = 218516835222. Its totient is φ = 218516835220.

The previous prime is 218516835169. The next prime is 218516835247. The reversal of 218516835221 is 122538615812.

218516835221 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., 144867016996 + 73649818225 = 380614^2 + 271385^2 .

It is a cyclic number.

It is not a de Polignac number, because 218516835221 - 2¹⁰ = 218516834197 is a prime.

It is a super-2 number, since 2×218516835221² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218516835421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109258417610 + 109258417611.

It is an arithmetic number, because the mean of its divisors is an integer number (109258417611).

Almost surely, 2^218516835221 is an apocalyptic number.

It is an amenable number.

218516835221 is a deficient number, since it is larger than the sum of its proper divisors (1).

218516835221 is an equidigital number, since it uses as much as digits as its factorization.

218516835221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 230400, while the sum is 44.

The spelling of 218516835221 in words is "two hundred eighteen billion, five hundred sixteen million, eight hundred thirty-five thousand, two hundred twenty-one".