21124800 has 210 divisors, whose sum is σ = 78125828. Its totient is φ = 5598720.

The previous prime is 21124783. The next prime is 21124801. The reversal of 21124800 is 842112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21124801) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 129519 + ... + 129681.

Almost surely, 2^21124800 is an apocalyptic number.

21124800 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 21124800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39062914).

21124800 is an abundant number, since it is smaller than the sum of its proper divisors (57001028).

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

21124800 is a wasteful number, since it uses less digits than its factorization.

21124800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 197 (or 173 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 21124800 is about 4596.1723205293. The cubic root of 21124800 is about 276.4378682907.

Adding to 21124800 its reverse (842112), we get a palindrome (21966912).

The spelling of 21124800 in words is "twenty-one million, one hundred twenty-four thousand, eight hundred".