6566581261 has 2 divisors, whose sum is σ = 6566581262. Its totient is φ = 6566581260.

The previous prime is 6566581193. The next prime is 6566581289. The reversal of 6566581261 is 1621856656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4885171236 + 1681410025 = 69894^2 + 41005^2 .

It is a cyclic number.

It is not a de Polignac number, because 6566581261 - 2⁹ = 6566580749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6566581291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3283290630 + 3283290631.

It is an arithmetic number, because the mean of its divisors is an integer number (3283290631).

Almost surely, 2^6566581261 is an apocalyptic number.

It is an amenable number.

6566581261 is a deficient number, since it is larger than the sum of its proper divisors (1).

6566581261 is an equidigital number, since it uses as much as digits as its factorization.

6566581261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 518400, while the sum is 46.

The square root of 6566581261 is about 81034.4449046207. Note that the first 3 decimals coincide. The cubic root of 6566581261 is about 1872.6061312047.

The spelling of 6566581261 in words is "six billion, five hundred sixty-six million, five hundred eighty-one thousand, two hundred sixty-one".