224821 has 4 divisors (see below), whose sum is σ = 225792. Its totient is φ = 223852.

The previous prime is 224813. The next prime is 224831. The reversal of 224821 is 128422.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 224821 - 2³ = 224813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (224831) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 90 + ... + 676.

It is an arithmetic number, because the mean of its divisors is an integer number (56448).

2²²⁴⁸²¹ is an apocalyptic number.

It is an amenable number.

224821 is a deficient number, since it is larger than the sum of its proper divisors (971).

224821 is an equidigital number, since it uses as much as digits as its factorization.

224821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 970.

The product of its digits is 256, while the sum is 19.

The square root of 224821 is about 474.1529289164. The cubic root of 224821 is about 60.8058865780.

The spelling of 224821 in words is "two hundred twenty-four thousand, eight hundred twenty-one".