21755055168 has 672 divisors, whose sum is σ = 82970754048. Its totient is φ = 5486745600.

The previous prime is 21755055137. The next prime is 21755055173. The reversal of 21755055168 is 86155055712.

21755055168 is a `hidden beast` number, since 21 + 75 + 5 + 0 + 551 + 6 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 44307403 + ... + 44307893.

It is an arithmetic number, because the mean of its divisors is an integer number (123468384).

Almost surely, 2^21755055168 is an apocalyptic number.

21755055168 is a gapful number since it is divisible by the number (28) 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 21755055168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41485377024).

21755055168 is an abundant number, since it is smaller than the sum of its proper divisors (61215698880).

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

21755055168 is a wasteful number, since it uses less digits than its factorization.

21755055168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 573 (or 551 counting only the distinct ones).

The product of its (nonzero) digits is 420000, while the sum is 45.

The spelling of 21755055168 in words is "twenty-one billion, seven hundred fifty-five million, fifty-five thousand, one hundred sixty-eight".