21027424 has 96 divisors (see below), whose sum is σ = 48771072. Its totient is φ = 8832000.

The previous prime is 21027421. The next prime is 21027443. The reversal of 21027424 is 42472012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21027395 and 21027404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21027421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 447369 + ... + 447415.

It is an arithmetic number, because the mean of its divisors is an integer number (508032).

Almost surely, 2^21027424 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 21027424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24385536).

21027424 is an abundant number, since it is smaller than the sum of its proper divisors (27743648).

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

21027424 is a wasteful number, since it uses less digits than its factorization.

21027424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 21027424 is about 4585.5669224208. The cubic root of 21027424 is about 276.0124618052.

Adding to 21027424 its reverse (42472012), we get a palindrome (63499436).

The spelling of 21027424 in words is "twenty-one million, twenty-seven thousand, four hundred twenty-four".