21864168 has 112 divisors (see below), whose sum is σ = 64530720. Its totient is φ = 6928416.

The previous prime is 21864121. The next prime is 21864187. The reversal of 21864168 is 86146812.

21864168 is a `hidden beast` number, since 2 + 1 + 8 + 641 + 6 + 8 = 666.

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 134055 + ... + 134217.

Almost surely, 2^21864168 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 21864168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32265360).

21864168 is an abundant number, since it is smaller than the sum of its proper divisors (42666552).

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

21864168 is a wasteful number, since it uses less digits than its factorization.

21864168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210 (or 191 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 21864168 is about 4675.9136005705. The cubic root of 21864168 is about 279.6260654659.

The spelling of 21864168 in words is "twenty-one million, eight hundred sixty-four thousand, one hundred sixty-eight".