21681043200 has 432 divisors, whose sum is σ = 80535644000. Its totient is φ = 5777879040.

The previous prime is 21681043183. The next prime is 21681043213. The reversal of 21681043200 is 234018612.

21681043200 is a `hidden beast` number, since 216 + 8 + 10 + 432 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (432).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13996026 + ... + 13997574.

Almost surely, 2^21681043200 is an apocalyptic number.

21681043200 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 21681043200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40267822000).

21681043200 is an abundant number, since it is smaller than the sum of its proper divisors (58854600800).

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

21681043200 is an frugal number, since it uses more digits than its factorization.

21681043200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1596 (or 1559 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The spelling of 21681043200 in words is "twenty-one billion, six hundred eighty-one million, forty-three thousand, two hundred".