21186912 has 48 divisors (see below), whose sum is σ = 56306880. Its totient is φ = 6974592.

The previous prime is 21186911. The next prime is 21186929. The reversal of 21186912 is 21968112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a self number, because there is not a number n which added to its sum of digits gives 21186912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21186911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6639 + ... + 9297.

It is an arithmetic number, because the mean of its divisors is an integer number (1173060).

Almost surely, 2^21186912 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 21186912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28153440).

21186912 is an abundant number, since it is smaller than the sum of its proper divisors (35119968).

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

21186912 is a wasteful number, since it uses less digits than its factorization.

21186912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2755 (or 2747 counting only the distinct ones).

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

The square root of 21186912 is about 4602.9242878848. The cubic root of 21186912 is about 276.7085344938.

The spelling of 21186912 in words is "twenty-one million, one hundred eighty-six thousand, nine hundred twelve".