21128955853824 has 2112 divisors, whose sum is σ = 83324515169280. Its totient is φ = 5146880901120.

The previous prime is 21128955853801. The next prime is 21128955853829. The reversal of 21128955853824 is 42835855982112.

21128955853824 is a `hidden beast` number, since 2 + 1 + 1 + 2 + 8 + 9 + 558 + 53 + 8 + 24 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128955853829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 39055370994 + ... + 39055371534.

It is an arithmetic number, because the mean of its divisors is an integer number (39452895440).

Almost surely, 2^{21128955853824} is an apocalyptic number.

21128955853824 is a gapful number since it is divisible by the number (24) 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 21128955853824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41662257584640).

21128955853824 is an abundant number, since it is smaller than the sum of its proper divisors (62195559315456).

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

21128955853824 is a wasteful number, since it uses less digits than its factorization.

21128955853824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 671 (or 628 counting only the distinct ones).

The product of its digits is 55296000, while the sum is 63.

The spelling of 21128955853824 in words is "twenty-one trillion, one hundred twenty-eight billion, nine hundred fifty-five million, eight hundred fifty-three thousand, eight hundred twenty-four".