12766661 has 4 divisors (see below), whose sum is σ = 12784812. Its totient is φ = 12748512.

The previous prime is 12766639. The next prime is 12766667. The reversal of 12766661 is 16666721.

12766661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16666721 = 1097 ⋅15193.

It can be written as a sum of positive squares in 2 ways, for example, as 12285025 + 481636 = 3505^2 + 694^2 .

It is a cyclic number.

It is not a de Polignac number, because 12766661 - 2¹⁸ = 12504517 is a prime.

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 (12766667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7976 + ... + 9441.

It is an arithmetic number, because the mean of its divisors is an integer number (3196203).

Almost surely, 2^12766661 is an apocalyptic number.

It is an amenable number.

12766661 is a deficient number, since it is larger than the sum of its proper divisors (18151).

12766661 is an equidigital number, since it uses as much as digits as its factorization.

12766661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18150.

The product of its digits is 18144, while the sum is 35.

The square root of 12766661 is about 3573.0464592557. The cubic root of 12766661 is about 233.7181511699.

The spelling of 12766661 in words is "twelve million, seven hundred sixty-six thousand, six hundred sixty-one".