21947884 has 48 divisors (see below), whose sum is σ = 47476800. Its totient is φ = 8843520.

The previous prime is 21947857. The next prime is 21947897. The reversal of 21947884 is 48874912.

It is a super-2 number, since 2×21947884² = 963419224154912, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21947884.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22854 + ... + 23794.

It is an arithmetic number, because the mean of its divisors is an integer number (989100).

Almost surely, 2^21947884 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 21947884, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23738400).

21947884 is an abundant number, since it is smaller than the sum of its proper divisors (25528916).

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

21947884 is a wasteful number, since it uses less digits than its factorization.

21947884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 983 (or 967 counting only the distinct ones).

The product of its digits is 129024, while the sum is 43.

The square root of 21947884 is about 4684.8568814853. The cubic root of 21947884 is about 279.9824989061.

The spelling of 21947884 in words is "twenty-one million, nine hundred forty-seven thousand, eight hundred eighty-four".