12665856621 has 48 divisors (see below), whose sum is σ = 18988058880. Its totient is φ = 7502352000.

The previous prime is 12665856611. The next prime is 12665856781.

12665856621 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 12665856621 - 2⁶ = 12665856557 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12665856611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2894191 + ... + 2898563.

It is an arithmetic number, because the mean of its divisors is an integer number (395584560).

Almost surely, 2^12665856621 is an apocalyptic number.

12665856621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12665856621 is a deficient number, since it is larger than the sum of its proper divisors (6322202259).

12665856621 is a wasteful number, since it uses less digits than its factorization.

12665856621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4578 (or 4567 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 48.

The spelling of 12665856621 in words is "twelve billion, six hundred sixty-five million, eight hundred fifty-six thousand, six hundred twenty-one".