21052724 has 48 divisors (see below), whose sum is σ = 47537280. Its totient is φ = 7916160.

The previous prime is 21052711. The next prime is 21052729. The reversal of 21052724 is 42725012.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21052724.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21052729) 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 15 ways as a sum of consecutive naturals, for example, 7754 + ... + 10110.

It is an arithmetic number, because the mean of its divisors is an integer number (990360).

Almost surely, 2^21052724 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21052724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23768640).

21052724 is an abundant number, since it is smaller than the sum of its proper divisors (26484556).

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

21052724 is a wasteful number, since it uses less digits than its factorization.

21052724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2408 (or 2406 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21052724 is about 4588.3247487509. The cubic root of 21052724 is about 276.1231159757.

Adding to 21052724 its reverse (42725012), we get a palindrome (63777736).

The spelling of 21052724 in words is "twenty-one million, fifty-two thousand, seven hundred twenty-four".