221918 has 16 divisors (see below), whose sum is σ = 361584. Its totient is φ = 101760.

The previous prime is 221909. The next prime is 221941. The reversal of 221918 is 819122.

221918 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 221893 and 221902.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221918.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2021 + ... + 2127.

It is an arithmetic number, because the mean of its divisors is an integer number (22599).

2²²¹⁹¹⁸ is an apocalyptic number.

221918 is a deficient number, since it is larger than the sum of its proper divisors (139666).

221918 is a wasteful number, since it uses less digits than its factorization.

221918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187.

The product of its digits is 288, while the sum is 23.

The square root of 221918 is about 471.0817338849. The cubic root of 221918 is about 60.5430333816.

The spelling of 221918 in words is "two hundred twenty-one thousand, nine hundred eighteen".