21159532800 has 1350 divisors, whose sum is σ = 96639256098. Its totient is φ = 4551966720.

The previous prime is 21159532787. The next prime is 21159532829. The reversal of 21159532800 is 823595112.

21159532800 is a `hidden beast` number, since 2 + 115 + 9 + 532 + 8 + 0 + 0 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 3186376704 + 17973156096 = 56448^2 + 134064^2 .

It is a tau number, because it is divible by the number of its divisors (1350).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 149 ways as a sum of consecutive naturals, for example, 1244678392 + ... + 1244678408.

Almost surely, 2^21159532800 is an apocalyptic number.

21159532800 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 21159532800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48319628049).

21159532800 is an abundant number, since it is smaller than the sum of its proper divisors (75479723298).

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

21159532800 is an frugal number, since it uses more digits than its factorization.

21159532800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The spelling of 21159532800 in words is "twenty-one billion, one hundred fifty-nine million, five hundred thirty-two thousand, eight hundred".