21168509868021 has 8 divisors (see below), whose sum is σ = 28271178475264. Its totient is φ = 14089090586400.

The previous prime is 21168509868017. The next prime is 21168509868029. The reversal of 21168509868021 is 12086890586112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21168509868021 - 2² = 21168509868017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21168509868029) 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 7 ways as a sum of consecutive naturals, for example, 5812329280 + ... + 5812332921.

It is an arithmetic number, because the mean of its divisors is an integer number (3533897309408).

Almost surely, 2^{21168509868021} is an apocalyptic number.

It is an amenable number.

21168509868021 is a deficient number, since it is larger than the sum of its proper divisors (7102668607243).

21168509868021 is a wasteful number, since it uses less digits than its factorization.

21168509868021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11624662811.

The product of its (nonzero) digits is 3317760, while the sum is 57.

The spelling of 21168509868021 in words is "twenty-one trillion, one hundred sixty-eight billion, five hundred nine million, eight hundred sixty-eight thousand, twenty-one".