21385223 has 4 divisors (see below), whose sum is σ = 21963240. Its totient is φ = 20807208.

The previous prime is 21385211. The next prime is 21385237. The reversal of 21385223 is 32258312.

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 21385223 - 2⁴ = 21385207 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21385192 and 21385201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21385253) 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, 288953 + ... + 289026.

It is an arithmetic number, because the mean of its divisors is an integer number (5490810).

Almost surely, 2^21385223 is an apocalyptic number.

21385223 is a deficient number, since it is larger than the sum of its proper divisors (578017).

21385223 is an equidigital number, since it uses as much as digits as its factorization.

21385223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 578016.

The product of its digits is 2880, while the sum is 26.

The square root of 21385223 is about 4624.4159631244. The cubic root of 21385223 is about 277.5691919554.

The spelling of 21385223 in words is "twenty-one million, three hundred eighty-five thousand, two hundred twenty-three".