21668065169 has 4 divisors (see below), whose sum is σ = 22415239860. Its totient is φ = 20920890480.

The previous prime is 21668065151. The next prime is 21668065183. The reversal of 21668065169 is 96156086612.

It is a happy number.

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 16022496400 + 5645568769 = 126580^2 + 75137^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21668065169 is a prime.

It is a super-2 number, since 2×21668065169² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21668065369) 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, 373587302 + ... + 373587359.

It is an arithmetic number, because the mean of its divisors is an integer number (5603809965).

Almost surely, 2^21668065169 is an apocalyptic number.

21668065169 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21668065169 is a deficient number, since it is larger than the sum of its proper divisors (747174691).

21668065169 is an equidigital number, since it uses as much as digits as its factorization.

21668065169 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 747174690.

The product of its (nonzero) digits is 933120, while the sum is 50.

The spelling of 21668065169 in words is "twenty-one billion, six hundred sixty-eight million, sixty-five thousand, one hundred sixty-nine".