21654022728520 has 128 divisors (see below), whose sum is σ = 59973292995840. Its totient is φ = 6852191892480.

The previous prime is 21654022728511. The next prime is 21654022728521. The reversal of 21654022728520 is 2582722045612.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21654022728521) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26101710 + ... + 26918530.

It is an arithmetic number, because the mean of its divisors is an integer number (468541351530).

Almost surely, 2^{21654022728520} is an apocalyptic number.

21654022728520 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 21654022728520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29986646497920).

21654022728520 is an abundant number, since it is smaller than the sum of its proper divisors (38319270267320).

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

21654022728520 is a wasteful number, since it uses less digits than its factorization.

21654022728520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 824135 (or 824131 counting only the distinct ones).

The product of its (nonzero) digits is 1075200, while the sum is 46.

The spelling of 21654022728520 in words is "twenty-one trillion, six hundred fifty-four billion, twenty-two million, seven hundred twenty-eight thousand, five hundred twenty".