12661616621 has 2 divisors, whose sum is σ = 12661616622. Its totient is φ = 12661616620.

The previous prime is 12661616599. The next prime is 12661616647.

It is a happy number.

12661616621 is nontrivially palindromic in base 10.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9937298596 + 2724318025 = 99686^2 + 52195^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 12661616621 - 2¹⁸ = 12661354477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12661616221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6330808310 + 6330808311.

It is an arithmetic number, because the mean of its divisors is an integer number (6330808311).

Almost surely, 2^12661616621 is an apocalyptic number.

It is an amenable number.

12661616621 is a deficient number, since it is larger than the sum of its proper divisors (1).

12661616621 is an equidigital number, since it uses as much as digits as its factorization.

12661616621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 38.

The spelling of 12661616621 in words is "twelve billion, six hundred sixty-one million, six hundred sixteen thousand, six hundred twenty-one".