21791867166869 has 2 divisors, whose sum is σ = 21791867166870. Its totient is φ = 21791867166868.

The previous prime is 21791867166829. The next prime is 21791867167003. The reversal of 21791867166869 is 96866176819712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15376107452644 + 6415759714225 = 3921238^2 + 2532935^2 .

It is a cyclic number.

It is not a de Polignac number, because 21791867166869 - 2²⁰ = 21791866118293 is a prime.

It is a super-2 number, since 2×21791867166869² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21791867166869.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21791867166809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10895933583434 + 10895933583435.

It is an arithmetic number, because the mean of its divisors is an integer number (10895933583435).

Almost surely, 2^{21791867166869} is an apocalyptic number.

It is an amenable number.

21791867166869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21791867166869 is an equidigital number, since it uses as much as digits as its factorization.

21791867166869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 658409472, while the sum is 77.

The spelling of 21791867166869 in words is "twenty-one trillion, seven hundred ninety-one billion, eight hundred sixty-seven million, one hundred sixty-six thousand, eight hundred sixty-nine".