21120424 has 32 divisors (see below), whose sum is σ = 44029440. Its totient is φ = 9432000.

The previous prime is 21120403. The next prime is 21120427. The reversal of 21120424 is 42402112.

It is a junction number, because it is equal to n+sod(n) for n = 21120398 and 21120407.

It is not an unprimeable number, because it can be changed into a prime (21120427) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52 + ... + 6499.

It is an arithmetic number, because the mean of its divisors is an integer number (1375920).

Almost surely, 2^21120424 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 21120424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22014720).

21120424 is an abundant number, since it is smaller than the sum of its proper divisors (22909016).

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

21120424 is a wasteful number, since it uses less digits than its factorization.

21120424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6601 (or 6597 counting only the distinct ones).

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

The square root of 21120424 is about 4595.6962475777. The cubic root of 21120424 is about 276.4187789478.

Adding to 21120424 its reverse (42402112), we get a palindrome (63522536).

The spelling of 21120424 in words is "twenty-one million, one hundred twenty thousand, four hundred twenty-four".