221618 has 8 divisors (see below), whose sum is σ = 343980. Its totient is φ = 106960.

The previous prime is 221603. The next prime is 221621. The reversal of 221618 is 816122.

221618 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 208849 + 12769 = 457^2 + 113^2 .

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

It is a super-2 number, since 2×221618² = 98229075848, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 221618.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221618.

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, 1853 + ... + 1968.

2²²¹⁶¹⁸ is an apocalyptic number.

221618 is a deficient number, since it is larger than the sum of its proper divisors (122362).

221618 is a wasteful number, since it uses less digits than its factorization.

221618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3852.

The product of its digits is 192, while the sum is 20.

The square root of 221618 is about 470.7632101174. The cubic root of 221618 is about 60.5157393651.

The spelling of 221618 in words is "two hundred twenty-one thousand, six hundred eighteen".