21444281 has 8 divisors (see below), whose sum is σ = 22192128. Its totient is φ = 20700000.

The previous prime is 21444263. The next prime is 21444287. The reversal of 21444281 is 18244412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21444281 is a prime.

It is a super-2 number, since 2×21444281² = 919714375213922, which contains 22 as substring.

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 21444281.

It is not an unprimeable number, because it can be changed into a prime (21444287) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18056 + ... + 19206.

It is an arithmetic number, because the mean of its divisors is an integer number (2774016).

Almost surely, 2^21444281 is an apocalyptic number.

It is an amenable number.

21444281 is a deficient number, since it is larger than the sum of its proper divisors (747847).

21444281 is a wasteful number, since it uses less digits than its factorization.

21444281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1783.

The product of its digits is 2048, while the sum is 26.

The square root of 21444281 is about 4630.7970156335. The cubic root of 21444281 is about 277.8244712557.

Adding to 21444281 its reverse (18244412), we get a palindrome (39688693).

The spelling of 21444281 in words is "twenty-one million, four hundred forty-four thousand, two hundred eighty-one".