21240544 has 24 divisors (see below), whose sum is σ = 45034920. Its totient is φ = 9803136.

The previous prime is 21240539. The next prime is 21240547. The reversal of 21240544 is 44504212.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240547) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25114 + ... + 25945.

It is an arithmetic number, because the mean of its divisors is an integer number (1876455).

Almost surely, 2^21240544 is an apocalyptic number.

It is an amenable number.

21240544 is an abundant number, since it is smaller than the sum of its proper divisors (23794376).

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

21240544 is a wasteful number, since it uses less digits than its factorization.

21240544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51082 (or 51074 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 22.

The square root of 21240544 is about 4608.7464673162. The cubic root of 21240544 is about 276.9418220296.

Adding to 21240544 its reverse (44504212), we get a palindrome (65744756).

The spelling of 21240544 in words is "twenty-one million, two hundred forty thousand, five hundred forty-four".