21085318800 has 540 divisors, whose sum is σ = 90570851904. Its totient is φ = 4447872000.

The previous prime is 21085318789. The next prime is 21085318853. The reversal of 21085318800 is 881358012.

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 107 ways as a sum of consecutive naturals, for example, 4256325 + ... + 4261275.

Almost surely, 2^21085318800 is an apocalyptic number.

21085318800 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 21085318800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45285425952).

21085318800 is an abundant number, since it is smaller than the sum of its proper divisors (69485533104).

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

21085318800 is a wasteful number, since it uses less digits than its factorization.

21085318800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5008 (or 4981 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 36.

The spelling of 21085318800 in words is "twenty-one billion, eighty-five million, three hundred eighteen thousand, eight hundred".