218223809 has 2 divisors, whose sum is σ = 218223810. Its totient is φ = 218223808.

The previous prime is 218223739. The next prime is 218223821. The reversal of 218223809 is 908322812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 212343184 + 5880625 = 14572^2 + 2425^2 .

It is a cyclic number.

It is not a de Polignac number, because 218223809 - 2⁸ = 218223553 is a prime.

It is not a weakly prime, because it can be changed into another prime (218226809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109111904 + 109111905.

It is an arithmetic number, because the mean of its divisors is an integer number (109111905).

Almost surely, 2^218223809 is an apocalyptic number.

It is an amenable number.

218223809 is a deficient number, since it is larger than the sum of its proper divisors (1).

218223809 is an equidigital number, since it uses as much as digits as its factorization.

218223809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 218223809 is about 14772.4002450516. The cubic root of 218223809 is about 602.0520561821.

The spelling of 218223809 in words is "two hundred eighteen million, two hundred twenty-three thousand, eight hundred nine".