21000885 has 16 divisors (see below), whose sum is σ = 33981120. Its totient is φ = 11073920.

The previous prime is 21000883. The next prime is 21000893. The reversal of 21000885 is 58800012.

It is not a de Polignac number, because 21000885 - 2¹ = 21000883 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000883) by changing a digit.

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, 6531 + ... + 9200.

It is an arithmetic number, because the mean of its divisors is an integer number (2123820).

Almost surely, 2^21000885 is an apocalyptic number.

It is an amenable number.

21000885 is a deficient number, since it is larger than the sum of its proper divisors (12980235).

21000885 is a wasteful number, since it uses less digits than its factorization.

21000885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15828.

The product of its (nonzero) digits is 640, while the sum is 24.

The square root of 21000885 is about 4582.6722553549. The cubic root of 21000885 is about 275.8962932153.

Adding to 21000885 its reverse (58800012), we get a palindrome (79800897).

The spelling of 21000885 in words is "twenty-one million, eight hundred eighty-five", and thus it is an aban number.