21189216 has 24 divisors (see below), whose sum is σ = 55621944. Its totient is φ = 7063040.

The previous prime is 21189173. The next prime is 21189221. The reversal of 21189216 is 61298112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (24).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110265 + ... + 110456.

It is an arithmetic number, because the mean of its divisors is an integer number (2317581).

Almost surely, 2^21189216 is an apocalyptic number.

It is an amenable number.

21189216 is an abundant number, since it is smaller than the sum of its proper divisors (34432728).

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

21189216 is a wasteful number, since it uses less digits than its factorization.

21189216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220734 (or 220726 counting only the distinct ones).

The product of its digits is 1728, while the sum is 30.

The square root of 21189216 is about 4603.1745567597. The cubic root of 21189216 is about 276.7185644808.

The spelling of 21189216 in words is "twenty-one million, one hundred eighty-nine thousand, two hundred sixteen".