21444307 has 4 divisors (see below), whose sum is σ = 21608136. Its totient is φ = 21280480.

The previous prime is 21444299. The next prime is 21444323. The reversal of 21444307 is 70344412.

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 21444307 - 2³ = 21444299 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21444347) 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, 81718 + ... + 81979.

It is an arithmetic number, because the mean of its divisors is an integer number (5402034).

Almost surely, 2^21444307 is an apocalyptic number.

21444307 is a deficient number, since it is larger than the sum of its proper divisors (163829).

21444307 is a wasteful number, since it uses less digits than its factorization.

21444307 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163828.

The product of its (nonzero) digits is 2688, while the sum is 25.

The square root of 21444307 is about 4630.7998229248. The cubic root of 21444307 is about 277.8245835379.

Adding to 21444307 its reverse (70344412), we get a palindrome (91788719).

It can be divided in two parts, 214 and 44307, that added together give a square (44521 = 211²).

The spelling of 21444307 in words is "twenty-one million, four hundred forty-four thousand, three hundred seven".