221868 has 18 divisors (see below), whose sum is σ = 560924. Its totient is φ = 73944.

The previous prime is 221849. The next prime is 221873. The reversal of 221868 is 868122.

221868 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (18).

It is an Ulam number.

It is a nialpdrome in base 6.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221868.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3046 + ... + 3117.

2²²¹⁸⁶⁸ is an apocalyptic number.

It is an amenable number.

221868 is an abundant number, since it is smaller than the sum of its proper divisors (339056).

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

221868 is a wasteful number, since it uses less digits than its factorization.

221868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6173 (or 6168 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 221868 is about 471.0286615483. The cubic root of 221868 is about 60.5384860878.

Subtracting from 221868 its sum of digits (27), we obtain a square (221841 = 471²).

It can be divided in two parts, 221 and 868, that added together give a square (1089 = 33²).

The spelling of 221868 in words is "two hundred twenty-one thousand, eight hundred sixty-eight".