222821 has 4 divisors (see below), whose sum is σ = 224352. Its totient is φ = 221292.

The previous prime is 222799. The next prime is 222823. The reversal of 222821 is 128222.

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.

It is a cyclic number.

It is not a de Polignac number, because 222821 - 2¹⁰ = 221797 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 222821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (222823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 521 + ... + 846.

It is an arithmetic number, because the mean of its divisors is an integer number (56088).

2²²²⁸²¹ is an apocalyptic number.

It is an amenable number.

222821 is a deficient number, since it is larger than the sum of its proper divisors (1531).

222821 is a wasteful number, since it uses less digits than its factorization.

222821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1530.

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

The square root of 222821 is about 472.0391932880. The cubic root of 222821 is about 60.6250402097.

The spelling of 222821 in words is "two hundred twenty-two thousand, eight hundred twenty-one".