12641540666 has 4 divisors (see below), whose sum is σ = 18962311002. Its totient is φ = 6320770332.

The previous prime is 12641540651. The next prime is 12641540719. The reversal of 12641540666 is 66604514621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66604514621 = 56599 ⋅1176779.

It can be written as a sum of positive squares in only one way, i.e., 6523954441 + 6117586225 = 80771^2 + 78215^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3160385165 + ... + 3160385168.

Almost surely, 2^12641540666 is an apocalyptic number.

12641540666 is a deficient number, since it is larger than the sum of its proper divisors (6320770336).

12641540666 is an equidigital number, since it uses as much as digits as its factorization.

12641540666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6320770335.

The product of its (nonzero) digits is 207360, while the sum is 41.

The spelling of 12641540666 in words is "twelve billion, six hundred forty-one million, five hundred forty thousand, six hundred sixty-six".