217218866809 has 4 divisors (see below), whose sum is σ = 248250133504. Its totient is φ = 186187600116.

The previous prime is 217218866747. The next prime is 217218866833. The reversal of 217218866809 is 908668812712.

It is a happy number.

217218866809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 217218866809 - 2²⁹ = 216681995897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217218866849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15515633337 + ... + 15515633350.

It is an arithmetic number, because the mean of its divisors is an integer number (62062533376).

Almost surely, 2^217218866809 is an apocalyptic number.

It is an amenable number.

217218866809 is a deficient number, since it is larger than the sum of its proper divisors (31031266695).

217218866809 is an equidigital number, since it uses as much as digits as its factorization.

217218866809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31031266694.

The product of its (nonzero) digits is 4644864, while the sum is 58.

The spelling of 217218866809 in words is "two hundred seventeen billion, two hundred eighteen million, eight hundred sixty-six thousand, eight hundred nine".