21011223 has 4 divisors (see below), whose sum is σ = 28014968. Its totient is φ = 14007480.

The previous prime is 21011191. The next prime is 21011231. The reversal of 21011223 is 32211012.

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

It is not a de Polignac number, because 21011223 - 2⁵ = 21011191 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011199 and 21011208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011233) 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, 3501868 + ... + 3501873.

It is an arithmetic number, because the mean of its divisors is an integer number (7003742).

Almost surely, 2^21011223 is an apocalyptic number.

21011223 is a deficient number, since it is larger than the sum of its proper divisors (7003745).

21011223 is an equidigital number, since it uses as much as digits as its factorization.

21011223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7003744.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21011223 is about 4583.8000610847. The cubic root of 21011223 is about 275.9415571488.

Adding to 21011223 its reverse (32211012), we get a palindrome (53222235).

The spelling of 21011223 in words is "twenty-one million, eleven thousand, two hundred twenty-three".