21044440 has 32 divisors (see below), whose sum is σ = 48005280. Its totient is φ = 8301312.

The previous prime is 21044431. The next prime is 21044467. The reversal of 21044440 is 4444012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 684 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (1500165).

Almost surely, 2^21044440 is an apocalyptic number.

21044440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21044440 is an abundant number, since it is smaller than the sum of its proper divisors (26960840).

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

21044440 is a wasteful number, since it uses less digits than its factorization.

21044440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7291 (or 7287 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21044440 is about 4587.4219339407. The cubic root of 21044440 is about 276.0868941550.

Adding to 21044440 its reverse (4444012), we get a palindrome (25488452).

The spelling of 21044440 in words is "twenty-one million, forty-four thousand, four hundred forty".