218091985 has 8 divisors (see below), whose sum is σ = 267278976. Its totient is φ = 170761200.

The previous prime is 218091971. The next prime is 218092009. The reversal of 218091985 is 589190812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 218091985 - 2⁹ = 218091473 is a prime.

It is a super-2 number, since 2×218091985² = 95128227842480450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 463791 + ... + 464260.

It is an arithmetic number, because the mean of its divisors is an integer number (33409872).

Almost surely, 2^218091985 is an apocalyptic number.

It is an amenable number.

218091985 is a deficient number, since it is larger than the sum of its proper divisors (49186991).

218091985 is an equidigital number, since it uses as much as digits as its factorization.

218091985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 928103.

The product of its (nonzero) digits is 51840, while the sum is 43.

The square root of 218091985 is about 14767.9377368677. The cubic root of 218091985 is about 601.9308031486.

The spelling of 218091985 in words is "two hundred eighteen million, ninety-one thousand, nine hundred eighty-five".