12666661 has 4 divisors (see below), whose sum is σ = 14476192. Its totient is φ = 10857132.

The previous prime is 12666607. The next prime is 12666671. The reversal of 12666661 is 16666621.

12666661 is nontrivially palindromic in base 11.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12666661 - 2²¹ = 10569509 is a prime.

It is a Duffinian number.

12666661 is an undulating number in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12666601) 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, 904755 + ... + 904768.

It is an arithmetic number, because the mean of its divisors is an integer number (3619048).

Almost surely, 2^12666661 is an apocalyptic number.

It is an amenable number.

12666661 is a deficient number, since it is larger than the sum of its proper divisors (1809531).

12666661 is an equidigital number, since it uses as much as digits as its factorization.

12666661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1809530.

The product of its digits is 15552, while the sum is 34.

The square root of 12666661 is about 3559.0252879124. The cubic root of 12666661 is about 233.1063204779.

It can be divided in two parts, 1 and 2666661, that added together give a palindrome (2666662).

The spelling of 12666661 in words is "twelve million, six hundred sixty-six thousand, six hundred sixty-one".