21668322735533 has 4 divisors (see below), whose sum is σ = 21680913279228. Its totient is φ = 21655732191840.

The previous prime is 21668322735491. The next prime is 21668322735551. The reversal of 21668322735533 is 33553722386612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12457807911844 + 9210514823689 = 3529562^2 + 3034883^2 .

It is a cyclic number.

It is not a de Polignac number, because 21668322735533 - 2³⁸ = 21393444828589 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 (21668322735133) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6295269266 + ... + 6295272707.

It is an arithmetic number, because the mean of its divisors is an integer number (5420228319807).

Almost surely, 2^{21668322735533} is an apocalyptic number.

It is an amenable number.

21668322735533 is a deficient number, since it is larger than the sum of its proper divisors (12590543695).

21668322735533 is a wasteful number, since it uses less digits than its factorization.

21668322735533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12590543694.

The product of its digits is 32659200, while the sum is 56.

The spelling of 21668322735533 in words is "twenty-one trillion, six hundred sixty-eight billion, three hundred twenty-two million, seven hundred thirty-five thousand, five hundred thirty-three".