218168261 has 2 divisors, whose sum is σ = 218168262. Its totient is φ = 218168260.

The previous prime is 218168213. The next prime is 218168263. The reversal of 218168261 is 162861812.

218168261 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., 118048225 + 100120036 = 10865^2 + 10006^2 .

It is a cyclic number.

It is not a de Polignac number, because 218168261 - 2¹⁴ = 218151877 is a prime.

Together with 218168263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218168263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109084130 + 109084131.

It is an arithmetic number, because the mean of its divisors is an integer number (109084131).

Almost surely, 2^218168261 is an apocalyptic number.

It is an amenable number.

218168261 is a deficient number, since it is larger than the sum of its proper divisors (1).

218168261 is an equidigital number, since it uses as much as digits as its factorization.

218168261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 35.

The square root of 218168261 is about 14770.5199976169. The cubic root of 218168261 is about 602.0009685308. Note that the first 3 decimals are identical.

The spelling of 218168261 in words is "two hundred eighteen million, one hundred sixty-eight thousand, two hundred sixty-one".