223821 has 12 divisors (see below), whose sum is σ = 348348. Its totient is φ = 137664.

The previous prime is 223781. The next prime is 223823. The reversal of 223821 is 128322.

223821 = T₁₁₈ + T₁₁₉ + ... + T₁₄₃.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 114921 + 108900 = 339^2 + 330^2 .

It is not a de Polignac number, because 223821 - 2⁶ = 223757 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 223794 and 223803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (223823) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 840 + ... + 1073.

It is an arithmetic number, because the mean of its divisors is an integer number (29029).

2²²³⁸²¹ is an apocalyptic number.

It is an amenable number.

223821 is a deficient number, since it is larger than the sum of its proper divisors (124527).

223821 is a wasteful number, since it uses less digits than its factorization.

223821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1932 (or 1929 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 223821 is about 473.0972415899. The cubic root of 223821 is about 60.7155980603.

The spelling of 223821 in words is "two hundred twenty-three thousand, eight hundred twenty-one".