221804 has 18 divisors (see below), whose sum is σ = 429492. Its totient is φ = 99400.

The previous prime is 221797. The next prime is 221807. The reversal of 221804 is 408122.

221804 = 17² + 18² + ... + 87².

221804 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a plaindrome in base 15.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221804.

It is not an unprimeable number, because it can be changed into a prime (221807) by changing a digit.

221804 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3089 + ... + 3159.

2²²¹⁸⁰⁴ is an apocalyptic number.

It is an amenable number.

221804 is a deficient number, since it is larger than the sum of its proper divisors (207688).

221804 is a wasteful number, since it uses less digits than its factorization.

221804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 221804 is about 470.9607202305. The cubic root of 221804 is about 60.5326645547.

Adding to 221804 its reverse (408122), we get a palindrome (629926).

The spelling of 221804 in words is "two hundred twenty-one thousand, eight hundred four".