21144223 has 2 divisors, whose sum is σ = 21144224. Its totient is φ = 21144222.

The previous prime is 21144203. The next prime is 21144229. The reversal of 21144223 is 32244112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21144223 - 2²¹ = 19047071 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21144223.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21144229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572111 + 10572112.

It is an arithmetic number, because the mean of its divisors is an integer number (10572112).

Almost surely, 2^21144223 is an apocalyptic number.

21144223 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144223 is an equidigital number, since it uses as much as digits as its factorization.

21144223 is an evil number, because the sum of its binary digits is even.

The product of its digits is 384, while the sum is 19.

The square root of 21144223 is about 4598.2847889186. The cubic root of 21144223 is about 276.5225650766.

Adding to 21144223 its reverse (32244112), we get a palindrome (53388335).

The spelling of 21144223 in words is "twenty-one million, one hundred forty-four thousand, two hundred twenty-three".