21441440 has 48 divisors (see below), whose sum is σ = 52413480. Its totient is φ = 8279040.

The previous prime is 21441421. The next prime is 21441449. The reversal of 21441440 is 4414412.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 16224784 + 5216656 = 4028^2 + 2284^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21441449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2330 + ... + 6950.

Almost surely, 2^21441440 is an apocalyptic number.

21441440 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 21441440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26206740).

21441440 is an abundant number, since it is smaller than the sum of its proper divisors (30972040).

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

21441440 is a wasteful number, since it uses less digits than its factorization.

21441440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4665 (or 4657 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

The square root of 21441440 is about 4630.4902548218. The cubic root of 21441440 is about 277.8122017190.

Adding to 21441440 its reverse (4414412), we get a palindrome (25855852).

The spelling of 21441440 in words is "twenty-one million, four hundred forty-one thousand, four hundred forty".