218908891 has 2 divisors, whose sum is σ = 218908892. Its totient is φ = 218908890.

The previous prime is 218908883. The next prime is 218908901. The reversal of 218908891 is 198809812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 218908891 - 2³ = 218908883 is a prime.

It is a super-2 number, since 2×218908891² = 95842205117699762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (218908831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109454445 + 109454446.

It is an arithmetic number, because the mean of its divisors is an integer number (109454446).

Almost surely, 2^218908891 is an apocalyptic number.

218908891 is a deficient number, since it is larger than the sum of its proper divisors (1).

218908891 is an equidigital number, since it uses as much as digits as its factorization.

218908891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82944, while the sum is 46.

The square root of 218908891 is about 14795.5699788822. The cubic root of 218908891 is about 602.6814164180.

The spelling of 218908891 in words is "two hundred eighteen million, nine hundred eight thousand, eight hundred ninety-one".