12661161521 has 2 divisors, whose sum is σ = 12661161522. Its totient is φ = 12661161520.

The previous prime is 12661161511. The next prime is 12661161523. The reversal of 12661161521 is 12516116621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6978263296 + 5682898225 = 83536^2 + 75385^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12661161521 is a prime.

It is a super-2 number, since 2×12661161521² (a number of 21 digits) contains 22 as substring.

Together with 12661161523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (12661161523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6330580760 + 6330580761.

It is an arithmetic number, because the mean of its divisors is an integer number (6330580761).

Almost surely, 2^12661161521 is an apocalyptic number.

It is an amenable number.

12661161521 is a deficient number, since it is larger than the sum of its proper divisors (1).

12661161521 is an equidigital number, since it uses as much as digits as its factorization.

12661161521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 32.

The spelling of 12661161521 in words is "twelve billion, six hundred sixty-one million, one hundred sixty-one thousand, five hundred twenty-one".