21009884 has 12 divisors (see below), whose sum is σ = 42019824. Its totient is φ = 9004224.

The previous prime is 21009883. The next prime is 21009887. The reversal of 21009884 is 48890012.

It is a happy number.

21009884 is an admirable number.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21009884.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21009883) 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 3 ways as a sum of consecutive naturals, for example, 375149 + ... + 375204.

It is an arithmetic number, because the mean of its divisors is an integer number (3501652).

Almost surely, 2^21009884 is an apocalyptic number.

It is an amenable number.

21009884 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21009884 is a wasteful number, since it uses less digits than its factorization.

21009884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 750364 (or 750362 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 21009884 is about 4583.6540009036. The cubic root of 21009884 is about 275.9356953039.

Adding to 21009884 its reverse (48890012), we get a palindrome (69899896).

The spelling of 21009884 in words is "twenty-one million, nine thousand, eight hundred eighty-four".