21444413 has 2 divisors, whose sum is σ = 21444414. Its totient is φ = 21444412.

The previous prime is 21444389. The next prime is 21444419. The reversal of 21444413 is 31444412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16345849 + 5098564 = 4043^2 + 2258^2 .

It is a cyclic number.

It is not a de Polignac number, because 21444413 - 2¹² = 21440317 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21444419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722206 + 10722207.

It is an arithmetic number, because the mean of its divisors is an integer number (10722207).

Almost surely, 2^21444413 is an apocalyptic number.

It is an amenable number.

21444413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21444413 is an equidigital number, since it uses as much as digits as its factorization.

21444413 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1536, while the sum is 23.

The square root of 21444413 is about 4630.8112680177. The cubic root of 21444413 is about 277.8250413029.

Adding to 21444413 its reverse (31444412), we get a palindrome (52888825).

Subtracting 21444413 from its reverse (31444412), we obtain a palindrome (9999999).

The spelling of 21444413 in words is "twenty-one million, four hundred forty-four thousand, four hundred thirteen".