21545856 has 96 divisors (see below), whose sum is σ = 63250200. Its totient is φ = 7037952.

The previous prime is 21545833. The next prime is 21545857. The reversal of 21545856 is 65854512.

21545856 is a `hidden beast` number, since 21 + 54 + 585 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

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 21545856.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21545857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 67810 + ... + 68126.

Almost surely, 2^21545856 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 21545856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31625100).

21545856 is an abundant number, since it is smaller than the sum of its proper divisors (41704344).

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

21545856 is a wasteful number, since it uses less digits than its factorization.

21545856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 396 (or 381 counting only the distinct ones).

The product of its digits is 48000, while the sum is 36.

The square root of 21545856 is about 4641.7513936013. The cubic root of 21545856 is about 278.2624369930.

The spelling of 21545856 in words is "twenty-one million, five hundred forty-five thousand, eight hundred fifty-six".