221806218 has 8 divisors (see below), whose sum is σ = 443612448. Its totient is φ = 73935404.

The previous prime is 221806141. The next prime is 221806229. The reversal of 221806218 is 812608122.

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

221806218 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18483846 + ... + 18483857.

It is an arithmetic number, because the mean of its divisors is an integer number (55451556).

Almost surely, 2^221806218 is an apocalyptic number.

221806218 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221806218 is a wasteful number, since it uses less digits than its factorization.

221806218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36967708.

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 221806218 is about 14893.1601079153. The cubic root of 221806218 is about 605.3286632598.

The spelling of 221806218 in words is "two hundred twenty-one million, eight hundred six thousand, two hundred eighteen".