218918709 has 12 divisors (see below), whose sum is σ = 327120300. Its totient is φ = 140913024.

The previous prime is 218918671. The next prime is 218918723. The reversal of 218918709 is 907819812.

It can be written as a sum of positive squares in 2 ways, for example, as 75637809 + 143280900 = 8697^2 + 11970^2 .

It is not a de Polignac number, because 218918709 - 2²¹ = 216821557 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218918789) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 419124 + ... + 419645.

It is an arithmetic number, because the mean of its divisors is an integer number (27260025).

Almost surely, 2^218918709 is an apocalyptic number.

218918709 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

218918709 is a deficient number, since it is larger than the sum of its proper divisors (108201591).

218918709 is a wasteful number, since it uses less digits than its factorization.

218918709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 838804 (or 838801 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 45.

The square root of 218918709 is about 14795.9017636642. The cubic root of 218918709 is about 602.6904263119.

The spelling of 218918709 in words is "two hundred eighteen million, nine hundred eighteen thousand, seven hundred nine".