21985056 has 72 divisors (see below), whose sum is σ = 65257920. Its totient is φ = 7007616.

The previous prime is 21985043. The next prime is 21985057. The reversal of 21985056 is 65058912.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21985056.

It is not an unprimeable number, because it can be changed into a prime (21985057) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 4965 + ... + 8283.

It is an arithmetic number, because the mean of its divisors is an integer number (906360).

Almost surely, 2^21985056 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 21985056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32628960).

21985056 is an abundant number, since it is smaller than the sum of its proper divisors (43272864).

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

21985056 is a wasteful number, since it uses less digits than its factorization.

21985056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3358 (or 3347 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 21985056 is about 4688.8224534525. The cubic root of 21985056 is about 280.1404737314.

The spelling of 21985056 in words is "twenty-one million, nine hundred eighty-five thousand, fifty-six".