218321091 has 12 divisors (see below), whose sum is σ = 315942640. Its totient is φ = 145275120.

The previous prime is 218321087. The next prime is 218321093. The reversal of 218321091 is 190123812.

It is not a de Polignac number, because 218321091 - 2² = 218321087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218321093) 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 in 11 ways as a sum of consecutive naturals, for example, 17551 + ... + 27288.

Almost surely, 2^218321091 is an apocalyptic number.

218321091 is a deficient number, since it is larger than the sum of its proper divisors (97621549).

218321091 is a wasteful number, since it uses less digits than its factorization.

218321091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45386 (or 45383 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 218321091 is about 14775.6925726004. The cubic root of 218321091 is about 602.1415058278.

The spelling of 218321091 in words is "two hundred eighteen million, three hundred twenty-one thousand, ninety-one".