21728520818568 has 192 divisors, whose sum is σ = 62543241633600. Its totient is φ = 6795448542720.

The previous prime is 21728520818567. The next prime is 21728520818569. The reversal of 21728520818568 is 86581802582712.

21728520818568 is a `hidden beast` number, since 2 + 1 + 7 + 2 + 8 + 52 + 0 + 8 + 18 + 568 = 666.

It is an interprime number because it is at equal distance from previous prime (21728520818567) and next prime (21728520818569).

It is not an unprimeable number, because it can be changed into a prime (21728520818561) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 524151730 + ... + 524193182.

It is an arithmetic number, because the mean of its divisors is an integer number (325746050175).

Almost surely, 2^{21728520818568} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21728520818568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31271620816800).

21728520818568 is an abundant number, since it is smaller than the sum of its proper divisors (40814720815032).

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

21728520818568 is a wasteful number, since it uses less digits than its factorization.

21728520818568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45172 (or 45165 counting only the distinct ones).

The product of its (nonzero) digits is 34406400, while the sum is 63.

The spelling of 21728520818568 in words is "twenty-one trillion, seven hundred twenty-eight billion, five hundred twenty million, eight hundred eighteen thousand, five hundred sixty-eight".