21443856 has 80 divisors (see below), whose sum is σ = 66662400. Its totient is φ = 5802624.

The previous prime is 21443827. The next prime is 21443881. The reversal of 21443856 is 65834412.

It is a super-3 number, since 3×21443856³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

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, 4705 + ... + 8063.

It is an arithmetic number, because the mean of its divisors is an integer number (833280).

Almost surely, 2^21443856 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 21443856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33331200).

21443856 is an abundant number, since it is smaller than the sum of its proper divisors (45218544).

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

21443856 is a wasteful number, since it uses less digits than its factorization.

21443856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3396 (or 3390 counting only the distinct ones).

The product of its digits is 23040, while the sum is 33.

The square root of 21443856 is about 4630.7511269771. The cubic root of 21443856 is about 277.8226358607.

The spelling of 21443856 in words is "twenty-one million, four hundred forty-three thousand, eight hundred fifty-six".