21865884 has 48 divisors (see below), whose sum is σ = 55574400. Its totient is φ = 6664896.

The previous prime is 21865843. The next prime is 21865891. The reversal of 21865884 is 48856812.

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 in 15 ways as a sum of consecutive naturals, for example, 4959 + ... + 8265.

It is an arithmetic number, because the mean of its divisors is an integer number (1157800).

Almost surely, 2^21865884 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21865884, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27787200).

21865884 is an abundant number, since it is smaller than the sum of its proper divisors (33708516).

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

21865884 is a wasteful number, since it uses less digits than its factorization.

21865884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3362 (or 3360 counting only the distinct ones).

The product of its digits is 122880, while the sum is 42.

The square root of 21865884 is about 4676.0970905232. The cubic root of 21865884 is about 279.6333807191.

The spelling of 21865884 in words is "twenty-one million, eight hundred sixty-five thousand, eight hundred eighty-four".