21918960 has 120 divisors (see below), whose sum is σ = 84146400. Its totient is φ = 5008896.

The previous prime is 21918881. The next prime is 21919003. The reversal of 21918960 is 6981912.

It is a tau number, because it is divible by the number of its divisors (120).

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

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 23 ways as a sum of consecutive naturals, for example, 2866 + ... + 7214.

It is an arithmetic number, because the mean of its divisors is an integer number (701220).

Almost surely, 2^21918960 is an apocalyptic number.

21918960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21918960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42073200).

21918960 is an abundant number, since it is smaller than the sum of its proper divisors (62227440).

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

21918960 is a wasteful number, since it uses less digits than its factorization.

21918960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4375 (or 4366 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 21918960 is about 4681.7688964749. The cubic root of 21918960 is about 279.8594532735.

The spelling of 21918960 in words is "twenty-one million, nine hundred eighteen thousand, nine hundred sixty".