21559078169 has 2 divisors, whose sum is σ = 21559078170. Its totient is φ = 21559078168.

The previous prime is 21559078157. The next prime is 21559078183. The reversal of 21559078169 is 96187095512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21210135769 + 348942400 = 145637^2 + 18680^2 .

It is a cyclic number.

It is not a de Polignac number, because 21559078169 - 2²⁴ = 21542300953 is a prime.

It is a super-2 number, since 2×21559078169² (a number of 21 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 21559078169.

It is not a weakly prime, because it can be changed into another prime (21559078769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10779539084 + 10779539085.

It is an arithmetic number, because the mean of its divisors is an integer number (10779539085).

Almost surely, 2^21559078169 is an apocalyptic number.

It is an amenable number.

21559078169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21559078169 is an equidigital number, since it uses as much as digits as its factorization.

21559078169 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1360800, while the sum is 53.

The spelling of 21559078169 in words is "twenty-one billion, five hundred fifty-nine million, seventy-eight thousand, one hundred sixty-nine".