218812261 has 2 divisors, whose sum is σ = 218812262. Its totient is φ = 218812260.

The previous prime is 218812259. The next prime is 218812277. The reversal of 218812261 is 162218812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 218123361 + 688900 = 14769^2 + 830^2 .

It is a cyclic number.

It is not a de Polignac number, because 218812261 - 2¹ = 218812259 is a prime.

Together with 218812259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218810261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109406130 + 109406131.

It is an arithmetic number, because the mean of its divisors is an integer number (109406131).

Almost surely, 2^218812261 is an apocalyptic number.

It is an amenable number.

218812261 is a deficient number, since it is larger than the sum of its proper divisors (1).

218812261 is an equidigital number, since it uses as much as digits as its factorization.

218812261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 31.

The square root of 218812261 is about 14792.3041139641. The cubic root of 218812261 is about 602.5927255231.

It can be divided in two parts, 21881 and 2261, that added together give a palindrome (24142).

The spelling of 218812261 in words is "two hundred eighteen million, eight hundred twelve thousand, two hundred sixty-one".