21043535 has 12 divisors (see below), whose sum is σ = 26826888. Its totient is φ = 15843456.

The previous prime is 21043523. The next prime is 21043543. The reversal of 21043535 is 53534012.

It is not a de Polignac number, because 21043535 - 2¹² = 21039439 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21043535.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5837 + ... + 8726.

It is an arithmetic number, because the mean of its divisors is an integer number (2235574).

Almost surely, 2^21043535 is an apocalyptic number.

21043535 is a deficient number, since it is larger than the sum of its proper divisors (5783353).

21043535 is a wasteful number, since it uses less digits than its factorization.

21043535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14602 (or 14585 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 21043535 is about 4587.3232935994. The cubic root of 21043535 is about 276.0829364632.

Adding to 21043535 its reverse (53534012), we get a palindrome (74577547).

The spelling of 21043535 in words is "twenty-one million, forty-three thousand, five hundred thirty-five".