21144423 has 4 divisors (see below), whose sum is σ = 28192568. Its totient is φ = 14096280.

The previous prime is 21144419. The next prime is 21144437. The reversal of 21144423 is 32444112.

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

It is not a de Polignac number, because 21144423 - 2² = 21144419 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21144423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144223) 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, 3524068 + ... + 3524073.

It is an arithmetic number, because the mean of its divisors is an integer number (7048142).

Almost surely, 2^21144423 is an apocalyptic number.

21144423 is a deficient number, since it is larger than the sum of its proper divisors (7048145).

21144423 is an equidigital number, since it uses as much as digits as its factorization.

21144423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7048144.

The product of its digits is 768, while the sum is 21.

The square root of 21144423 is about 4598.3065361065. The cubic root of 21144423 is about 276.5234369355.

Adding to 21144423 its reverse (32444112), we get a palindrome (53588535).

The spelling of 21144423 in words is "twenty-one million, one hundred forty-four thousand, four hundred twenty-three".