2661256516169 has 2 divisors, whose sum is σ = 2661256516170. Its totient is φ = 2661256516168.

The previous prime is 2661256516129. The next prime is 2661256516199. The reversal of 2661256516169 is 9616156521662.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1545951549769 + 1115304966400 = 1243363^2 + 1056080^2 .

It is a cyclic number.

It is not a de Polignac number, because 2661256516169 - 2⁸ = 2661256515913 is a prime.

It is a super-2 number, since 2×2661256516169² (a number of 26 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2661256516129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1330628258084 + 1330628258085.

It is an arithmetic number, because the mean of its divisors is an integer number (1330628258085).

Almost surely, 2^{2661256516169} is an apocalyptic number.

It is an amenable number.

2661256516169 is a deficient number, since it is larger than the sum of its proper divisors (1).

2661256516169 is an equidigital number, since it uses as much as digits as its factorization.

2661256516169 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6998400, while the sum is 56.

The spelling of 2661256516169 in words is "two trillion, six hundred sixty-one billion, two hundred fifty-six million, five hundred sixteen thousand, one hundred sixty-nine".