21104440 has 64 divisors (see below), whose sum is σ = 57139200. Its totient is φ = 6853248.

The previous prime is 21104407. The next prime is 21104453. The reversal of 21104440 is 4440112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3337 + ... + 7303.

It is an arithmetic number, because the mean of its divisors is an integer number (892800).

Almost surely, 2^21104440 is an apocalyptic number.

21104440 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 21104440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28569600).

21104440 is an abundant number, since it is smaller than the sum of its proper divisors (36034760).

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

21104440 is a wasteful number, since it uses less digits than its factorization.

21104440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4004 (or 4000 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21104440 is about 4593.9569001026. The cubic root of 21104440 is about 276.3490298301.

Adding to 21104440 its reverse (4440112), we get a palindrome (25544552).

The spelling of 21104440 in words is "twenty-one million, one hundred four thousand, four hundred forty".