21040024 has 16 divisors (see below), whose sum is σ = 39535200. Its totient is φ = 10497312.

The previous prime is 21040007. The next prime is 21040039. The reversal of 21040024 is 42004012.

It is a junction number, because it is equal to n+sod(n) for n = 21039986 and 21040013.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1489 + ... + 6655.

It is an arithmetic number, because the mean of its divisors is an integer number (2470950).

Almost surely, 2^21040024 is an apocalyptic number.

It is an amenable number.

21040024 is a deficient number, since it is larger than the sum of its proper divisors (18495176).

21040024 is a wasteful number, since it uses less digits than its factorization.

21040024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5682 (or 5678 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 21040024 is about 4586.9405925955. The cubic root of 21040024 is about 276.0675812943.

Adding to 21040024 its reverse (42004012), we get a palindrome (63044036).

The spelling of 21040024 in words is "twenty-one million, forty thousand, twenty-four".