1266555517 has 2 divisors, whose sum is σ = 1266555518. Its totient is φ = 1266555516.

The previous prime is 1266555449. The next prime is 1266555557. The reversal of 1266555517 is 7155556621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 702303001 + 564252516 = 26501^2 + 23754^2 .

It is an emirp because it is prime and its reverse (7155556621) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1266555517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1266555557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633277758 + 633277759.

It is an arithmetic number, because the mean of its divisors is an integer number (633277759).

Almost surely, 2^1266555517 is an apocalyptic number.

It is an amenable number.

1266555517 is a deficient number, since it is larger than the sum of its proper divisors (1).

1266555517 is an equidigital number, since it uses as much as digits as its factorization.

1266555517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 315000, while the sum is 43.

The square root of 1266555517 is about 35588.6992878357. The cubic root of 1266555517 is about 1081.9522066646.

The spelling of 1266555517 in words is "one billion, two hundred sixty-six million, five hundred fifty-five thousand, five hundred seventeen".