21156106605169 has 2 divisors, whose sum is σ = 21156106605170. Its totient is φ = 21156106605168.

The previous prime is 21156106605113. The next prime is 21156106605223. The reversal of 21156106605169 is 96150660165112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15729592263025 + 5426514342144 = 3966055^2 + 2329488^2 .

It is a cyclic number.

It is not a de Polignac number, because 21156106605169 - 2⁹ = 21156106604657 is a prime.

It is a super-2 number, since 2×21156106605169² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21156106605869) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578053302584 + 10578053302585.

It is an arithmetic number, because the mean of its divisors is an integer number (10578053302585).

Almost surely, 2^{21156106605169} is an apocalyptic number.

It is an amenable number.

21156106605169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21156106605169 is an equidigital number, since it uses as much as digits as its factorization.

21156106605169 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 583200, while the sum is 49.

The spelling of 21156106605169 in words is "twenty-one trillion, one hundred fifty-six billion, one hundred six million, six hundred five thousand, one hundred sixty-nine".