21004024 has 8 divisors (see below), whose sum is σ = 39382560. Its totient is φ = 10502008.

The previous prime is 21003937. The next prime is 21004043. The reversal of 21004024 is 42040012.

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21003995 and 21004013.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1312744 + ... + 1312759.

It is an arithmetic number, because the mean of its divisors is an integer number (4922820).

Almost surely, 2^21004024 is an apocalyptic number.

It is an amenable number.

21004024 is a deficient number, since it is larger than the sum of its proper divisors (18378536).

21004024 is a wasteful number, since it uses less digits than its factorization.

21004024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2625509 (or 2625505 counting only the distinct ones).

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

The square root of 21004024 is about 4583.0147283202. The cubic root of 21004024 is about 275.9100385934.

Adding to 21004024 its reverse (42040012), we get a palindrome (63044036).

The spelling of 21004024 in words is "twenty-one million, four thousand, twenty-four".