218616389 has 2 divisors, whose sum is σ = 218616390. Its totient is φ = 218616388.

The previous prime is 218616347. The next prime is 218616397. The reversal of 218616389 is 983616812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 218596225 + 20164 = 14785^2 + 142^2 .

It is a cyclic number.

It is not a de Polignac number, because 218616389 - 2⁸ = 218616133 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218616319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109308194 + 109308195.

It is an arithmetic number, because the mean of its divisors is an integer number (109308195).

Almost surely, 2^218616389 is an apocalyptic number.

It is an amenable number.

218616389 is a deficient number, since it is larger than the sum of its proper divisors (1).

218616389 is an equidigital number, since it uses as much as digits as its factorization.

218616389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 44.

The square root of 218616389 is about 14785.6818916139. The cubic root of 218616389 is about 602.4128661950.

The spelling of 218616389 in words is "two hundred eighteen million, six hundred sixteen thousand, three hundred eighty-nine".