21444280 has 128 divisors (see below), whose sum is σ = 59512320. Its totient is φ = 6842880.

The previous prime is 21444263. The next prime is 21444287. The reversal of 21444280 is 8244412.

It is a congruent number.

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

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 131479 + ... + 131641.

It is an arithmetic number, because the mean of its divisors is an integer number (464940).

Almost surely, 2^21444280 is an apocalyptic number.

21444280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21444280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29756160).

21444280 is an abundant number, since it is smaller than the sum of its proper divisors (38068040).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21444280 is a wasteful number, since it uses less digits than its factorization.

21444280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221 (or 217 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 25.

The square root of 21444280 is about 4630.7969076607. The cubic root of 21444280 is about 277.8244669372.

Adding to 21444280 its reverse (8244412), we get a palindrome (29688692).

The spelling of 21444280 in words is "twenty-one million, four hundred forty-four thousand, two hundred eighty".