218885561 has 2 divisors, whose sum is σ = 218885562. Its totient is φ = 218885560.

The previous prime is 218885543. The next prime is 218885573. The reversal of 218885561 is 165588812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185477161 + 33408400 = 13619^2 + 5780^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-218885561 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (218885461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109442780 + 109442781.

It is an arithmetic number, because the mean of its divisors is an integer number (109442781).

Almost surely, 2^218885561 is an apocalyptic number.

It is an amenable number.

218885561 is a deficient number, since it is larger than the sum of its proper divisors (1).

218885561 is an equidigital number, since it uses as much as digits as its factorization.

218885561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 153600, while the sum is 44.

The square root of 218885561 is about 14794.7815462074. The cubic root of 218885561 is about 602.6600055974.

The spelling of 218885561 in words is "two hundred eighteen million, eight hundred eighty-five thousand, five hundred sixty-one".