218105509 has 2 divisors, whose sum is σ = 218105510. Its totient is φ = 218105508.

The previous prime is 218105501. The next prime is 218105513. The reversal of 218105509 is 905501812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134328100 + 83777409 = 11590^2 + 9153^2 .

It is a cyclic number.

It is not a de Polignac number, because 218105509 - 2³ = 218105501 is a prime.

It is a super-2 number, since 2×218105509² = 95140026112298162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (218105501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109052754 + 109052755.

It is an arithmetic number, because the mean of its divisors is an integer number (109052755).

Almost surely, 2^218105509 is an apocalyptic number.

It is an amenable number.

218105509 is a deficient number, since it is larger than the sum of its proper divisors (1).

218105509 is an equidigital number, since it uses as much as digits as its factorization.

218105509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 31.

The square root of 218105509 is about 14768.3956136068. The cubic root of 218105509 is about 601.9432449079.

The spelling of 218105509 in words is "two hundred eighteen million, one hundred five thousand, five hundred nine".