1266555557 has 2 divisors, whose sum is σ = 1266555558. Its totient is φ = 1266555556.

The previous prime is 1266555517. The next prime is 1266555569. The reversal of 1266555557 is 7555556621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1123657441 + 142898116 = 33521^2 + 11954^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266555557 - 2¹⁴ = 1266539173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1266555517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633277778 + 633277779.

It is an arithmetic number, because the mean of its divisors is an integer number (633277779).

Almost surely, 2^1266555557 is an apocalyptic number.

It is an amenable number.

1266555557 is a deficient number, since it is larger than the sum of its proper divisors (1).

1266555557 is an equidigital number, since it uses as much as digits as its factorization.

1266555557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1575000, while the sum is 47.

The square root of 1266555557 is about 35588.6998498119. The cubic root of 1266555557 is about 1081.9522180546.

The spelling of 1266555557 in words is "one billion, two hundred sixty-six million, five hundred fifty-five thousand, five hundred fifty-seven".