12666581 has 12 divisors (see below), whose sum is σ = 13796580. Its totient is φ = 11619840.

The previous prime is 12666571. The next prime is 12666587. The reversal of 12666581 is 18566621.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 100 + 12666481 = 10^2 + 3559^2 .

It is not a de Polignac number, because 12666581 - 2⁶ = 12666517 is a prime.

It is a super-2 number, since 2×12666581² = 320884548459122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12666587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11315 + ... + 12383.

It is an arithmetic number, because the mean of its divisors is an integer number (1149715).

Almost surely, 2^12666581 is an apocalyptic number.

It is an amenable number.

12666581 is a deficient number, since it is larger than the sum of its proper divisors (1129999).

12666581 is a wasteful number, since it uses less digits than its factorization.

12666581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1144 (or 1127 counting only the distinct ones).

The product of its digits is 17280, while the sum is 35.

The square root of 12666581 is about 3559.0140488624. The cubic root of 12666581 is about 233.1058297265.

The spelling of 12666581 in words is "twelve million, six hundred sixty-six thousand, five hundred eighty-one".