218209081 has 8 divisors (see below), whose sum is σ = 223068960. Its totient is φ = 213388032.

The previous prime is 218209067. The next prime is 218209087. The reversal of 218209081 is 180902812.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 218209081 - 2⁵ = 218209049 is a prime.

It is a super-2 number, since 2×218209081² = 95230406061729122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218209087) 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 in 7 ways as a sum of consecutive naturals, for example, 1806 + ... + 20968.

It is an arithmetic number, because the mean of its divisors is an integer number (27883620).

Almost surely, 2^218209081 is an apocalyptic number.

It is an amenable number.

218209081 is a deficient number, since it is larger than the sum of its proper divisors (4859879).

218209081 is a wasteful number, since it uses less digits than its factorization.

218209081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19415.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 218209081 is about 14771.9017394512. The cubic root of 218209081 is about 602.0385116439.

The spelling of 218209081 in words is "two hundred eighteen million, two hundred nine thousand, eighty-one".