21820223 has 4 divisors (see below), whose sum is σ = 21835008. Its totient is φ = 21805440.

The previous prime is 21820213. The next prime is 21820243. The reversal of 21820223 is 32202812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21820223 - 2⁴ = 21820207 is a prime.

It is a super-2 number, since 2×21820223² = 952244263539458, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21820195 and 21820204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820213) 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, 4898 + ... + 8223.

It is an arithmetic number, because the mean of its divisors is an integer number (5458752).

Almost surely, 2^21820223 is an apocalyptic number.

21820223 is a deficient number, since it is larger than the sum of its proper divisors (14785).

21820223 is a wasteful number, since it uses less digits than its factorization.

21820223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14784.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21820223 is about 4671.2121553190. The cubic root of 21820223 is about 279.4385987798.

The spelling of 21820223 in words is "twenty-one million, eight hundred twenty thousand, two hundred twenty-three".