21144024 has 96 divisors (see below), whose sum is σ = 64638000. Its totient is φ = 6399360.

The previous prime is 21143999. The next prime is 21144029. The reversal of 21144024 is 42044112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21143988 and 21144006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144029) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25732 + ... + 26540.

Almost surely, 2^21144024 is an apocalyptic number.

21144024 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21144024, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32319000).

21144024 is an abundant number, since it is smaller than the sum of its proper divisors (43493976).

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

21144024 is a wasteful number, since it uses less digits than its factorization.

21144024 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 846 (or 825 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 21144024 is about 4598.2631503645. The cubic root of 21144024 is about 276.5216975715.

Adding to 21144024 its reverse (42044112), we get a palindrome (63188136).

The spelling of 21144024 in words is "twenty-one million, one hundred forty-four thousand, twenty-four".