21517768848161 has 8 divisors (see below), whose sum is σ = 22391371606560. Its totient is φ = 20661129250272.

The previous prime is 21517768848139. The next prime is 21517768848193. The reversal of 21517768848161 is 16184886771512.

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

It is a cyclic number.

It is not a de Polignac number, because 21517768848161 - 2²⁶ = 21517701739297 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21517768848361) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4240787540 + ... + 4240792613.

It is an arithmetic number, because the mean of its divisors is an integer number (2798921450820).

Almost surely, 2^{21517768848161} is an apocalyptic number.

It is an amenable number.

21517768848161 is a deficient number, since it is larger than the sum of its proper divisors (873602758399).

21517768848161 is an equidigital number, since it uses as much as digits as its factorization.

21517768848161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8481580255.

The product of its digits is 36126720, while the sum is 65.

The spelling of 21517768848161 in words is "twenty-one trillion, five hundred seventeen billion, seven hundred sixty-eight million, eight hundred forty-eight thousand, one hundred sixty-one".