21043885 has 16 divisors (see below), whose sum is σ = 26284032. Its totient is φ = 16156800.

The previous prime is 21043871. The next prime is 21043901. The reversal of 21043885 is 58834012.

It is not a de Polignac number, because 21043885 - 2²³ = 12655277 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

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 15 ways as a sum of consecutive naturals, for example, 20740 + ... + 21730.

It is an arithmetic number, because the mean of its divisors is an integer number (1642752).

Almost surely, 2^21043885 is an apocalyptic number.

It is an amenable number.

21043885 is a deficient number, since it is larger than the sum of its proper divisors (5240147).

21043885 is a wasteful number, since it uses less digits than its factorization.

21043885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1164.

The product of its (nonzero) digits is 7680, while the sum is 31.

The square root of 21043885 is about 4587.3614420492. The cubic root of 21043885 is about 276.0844670757.

Adding to 21043885 its reverse (58834012), we get a palindrome (79877897).

The spelling of 21043885 in words is "twenty-one million, forty-three thousand, eight hundred eighty-five".