218308609 has 2 divisors, whose sum is σ = 218308610. Its totient is φ = 218308608.

The previous prime is 218308589. The next prime is 218308631. The reversal of 218308609 is 906803812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 119246400 + 99062209 = 10920^2 + 9953^2 .

It is a cyclic number.

It is not a de Polignac number, because 218308609 - 2⁷ = 218308481 is a prime.

It is not a weakly prime, because it can be changed into another prime (218305609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109154304 + 109154305.

It is an arithmetic number, because the mean of its divisors is an integer number (109154305).

Almost surely, 2^218308609 is an apocalyptic number.

It is an amenable number.

218308609 is a deficient number, since it is larger than the sum of its proper divisors (1).

218308609 is an equidigital number, since it uses as much as digits as its factorization.

218308609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 218308609 is about 14775.2701836548. The cubic root of 218308609 is about 602.1300302629.

The spelling of 218308609 in words is "two hundred eighteen million, three hundred eight thousand, six hundred nine".