20981721600 has 1200 divisors, whose sum is σ = 92094552000. Its totient is φ = 4714536960.

The previous prime is 20981721569. The next prime is 20981721619. The reversal of 20981721600 is 612718902.

20981721600 is a `hidden beast` number, since 20 + 9 + 8 + 1 + 7 + 21 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (1200).

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 119 ways as a sum of consecutive naturals, for example, 355622371 + ... + 355622429.

It is an arithmetic number, because the mean of its divisors is an integer number (76745460).

Almost surely, 2^20981721600 is an apocalyptic number.

20981721600 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 20981721600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46047276000).

20981721600 is an abundant number, since it is smaller than the sum of its proper divisors (71112830400).

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

20981721600 is an frugal number, since it uses more digits than its factorization.

20981721600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120 (or 76 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The spelling of 20981721600 in words is "twenty billion, nine hundred eighty-one million, seven hundred twenty-one thousand, six hundred".