12666557 has 2 divisors, whose sum is σ = 12666558. Its totient is φ = 12666556.

The previous prime is 12666539. The next prime is 12666571. The reversal of 12666557 is 75566621.

12666557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6446521 + 6220036 = 2539^2 + 2494^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12666557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 12666557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12666517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6333278 + 6333279.

It is an arithmetic number, because the mean of its divisors is an integer number (6333279).

Almost surely, 2^12666557 is an apocalyptic number.

It is an amenable number.

12666557 is a deficient number, since it is larger than the sum of its proper divisors (1).

12666557 is an equidigital number, since it uses as much as digits as its factorization.

12666557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75600, while the sum is 38.

The square root of 12666557 is about 3559.0106771405. The cubic root of 12666557 is about 233.1056825007.

The spelling of 12666557 in words is "twelve million, six hundred sixty-six thousand, five hundred fifty-seven".