21724800 has 192 divisors, whose sum is σ = 74876160. Its totient is φ = 5529600.

The previous prime is 21724783. The next prime is 21724819. The reversal of 21724800 is 842712.

It is a tau number, because it is divible by the number of its divisors (192).

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 297564 + ... + 297636.

It is an arithmetic number, because the mean of its divisors is an integer number (389980).

Almost surely, 2^21724800 is an apocalyptic number.

21724800 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 21724800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37438080).

21724800 is an abundant number, since it is smaller than the sum of its proper divisors (53151360).

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

21724800 is a wasteful number, since it uses less digits than its factorization.

21724800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 21724800 is about 4660.9870199347. The cubic root of 21724800 is about 279.0306617039.

The spelling of 21724800 in words is "twenty-one million, seven hundred twenty-four thousand, eight hundred".