21845646 has 64 divisors (see below), whose sum is σ = 52488000. Its totient is φ = 6709248.

The previous prime is 21845627. The next prime is 21845689. The reversal of 21845646 is 64654812.

21845646 is a `hidden beast` number, since 2 + 1 + 8 + 4 + 5 + 646 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21845646.

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 31 ways as a sum of consecutive naturals, for example, 48430 + ... + 48878.

It is an arithmetic number, because the mean of its divisors is an integer number (820125).

Almost surely, 2^21845646 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21845646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26244000).

21845646 is an abundant number, since it is smaller than the sum of its proper divisors (30642354).

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

21845646 is a wasteful number, since it uses less digits than its factorization.

21845646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530 (or 524 counting only the distinct ones).

The product of its digits is 46080, while the sum is 36.

The square root of 21845646 is about 4673.9326054191. The cubic root of 21845646 is about 279.5470823982.

The spelling of 21845646 in words is "twenty-one million, eight hundred forty-five thousand, six hundred forty-six".