21128200 has 48 divisors (see below), whose sum is σ = 49522500. Its totient is φ = 8382720.

The previous prime is 21128197. The next prime is 21128201. The reversal of 21128200 is 282112.

It can be written as a sum of positive squares in 6 ways, for example, as 1004004 + 20124196 = 1002^2 + 4486^2 .

It is not an unprimeable number, because it can be changed into a prime (21128201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29446 + ... + 30154.

Almost surely, 2^21128200 is an apocalyptic number.

21128200 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 21128200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24761250).

21128200 is an abundant number, since it is smaller than the sum of its proper divisors (28394300).

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

21128200 is a wasteful number, since it uses less digits than its factorization.

21128200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 874 (or 865 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 21128200 is about 4596.5421786382. The cubic root of 21128200 is about 276.4526982273.

The spelling of 21128200 in words is "twenty-one million, one hundred twenty-eight thousand, two hundred".