21109200 has 180 divisors, whose sum is σ = 78878880. Its totient is φ = 4811520.

The previous prime is 21109181. The next prime is 21109201. The reversal of 21109200 is 290112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21109200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21109201) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 58621 + ... + 58979.

It is an arithmetic number, because the mean of its divisors is an integer number (438216).

Almost surely, 2^21109200 is an apocalyptic number.

21109200 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 21109200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39439440).

21109200 is an abundant number, since it is smaller than the sum of its proper divisors (57769680).

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

21109200 is a wasteful number, since it uses less digits than its factorization.

21109200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394 (or 376 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 21109200 is about 4594.4749427981. The cubic root of 21109200 is about 276.3698046449.

Adding to 21109200 its reverse (290112), we get a palindrome (21399312).

The spelling of 21109200 in words is "twenty-one million, one hundred nine thousand, two hundred".