21668268671 has 16 divisors (see below), whose sum is σ = 25974168576. Its totient is φ = 17686338336.

The previous prime is 21668268649. The next prime is 21668268701. The reversal of 21668268671 is 17686286612.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21668268671 - 2¹⁸ = 21668006527 is a prime.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21668268641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 877841 + ... + 902186.

It is an arithmetic number, because the mean of its divisors is an integer number (1623385536).

Almost surely, 2^21668268671 is an apocalyptic number.

21668268671 is a deficient number, since it is larger than the sum of its proper divisors (4305899905).

21668268671 is a wasteful number, since it uses less digits than its factorization.

21668268671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1780118.

The product of its digits is 2322432, while the sum is 53.

The spelling of 21668268671 in words is "twenty-one billion, six hundred sixty-eight million, two hundred sixty-eight thousand, six hundred seventy-one".