21288800 has 144 divisors (see below), whose sum is σ = 59058720. Its totient is φ = 7434240.

The previous prime is 21288779. The next prime is 21288829. The reversal of 21288800 is 888212.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 239156 + ... + 239244.

It is an arithmetic number, because the mean of its divisors is an integer number (410130).

Almost surely, 2^21288800 is an apocalyptic number.

21288800 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 21288800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29529360).

21288800 is an abundant number, since it is smaller than the sum of its proper divisors (37769920).

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

21288800 is a wasteful number, since it uses less digits than its factorization.

21288800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145 (or 132 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 29.

The square root of 21288800 is about 4613.9787602459. The cubic root of 21288800 is about 277.1513897438.

The spelling of 21288800 in words is "twenty-one million, two hundred eighty-eight thousand, eight hundred".