20561104800 has 216 divisors, whose sum is σ = 75189625056. Its totient is φ = 5482909440.

The previous prime is 20561104789. The next prime is 20561104813. The reversal of 20561104800 is 840116502.

20561104800 is a `hidden beast` number, since 2 + 0 + 5 + 611 + 0 + 48 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (216).

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 polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 141517 + ... + 247283.

It is an arithmetic number, because the mean of its divisors is an integer number (348100116).

Almost surely, 2^20561104800 is an apocalyptic number.

20561104800 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 20561104800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37594812528).

20561104800 is an abundant number, since it is smaller than the sum of its proper divisors (54628520256).

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

20561104800 is a wasteful number, since it uses less digits than its factorization.

20561104800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105802 (or 105777 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The spelling of 20561104800 in words is "twenty billion, five hundred sixty-one million, one hundred four thousand, eight hundred".