21918168 has 128 divisors (see below), whose sum is σ = 66355200. Its totient is φ = 6676992.

The previous prime is 21918161. The next prime is 21918173. The reversal of 21918168 is 86181912.

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 not an unprimeable number, because it can be changed into a prime (21918161) 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 31 ways as a sum of consecutive naturals, for example, 172521 + ... + 172647.

It is an arithmetic number, because the mean of its divisors is an integer number (518400).

Almost surely, 2^21918168 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 21918168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33177600).

21918168 is an abundant number, since it is smaller than the sum of its proper divisors (44437032).

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

21918168 is a wasteful number, since it uses less digits than its factorization.

21918168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206 (or 196 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 21918168 is about 4681.6843122962. The cubic root of 21918168 is about 279.8560825030.

The spelling of 21918168 in words is "twenty-one million, nine hundred eighteen thousand, one hundred sixty-eight".