12128561 has 2 divisors, whose sum is σ = 12128562. Its totient is φ = 12128560.

The previous prime is 12128513. The next prime is 12128587. The reversal of 12128561 is 16582121.

It is an a-pointer prime, because the next prime (12128587) can be obtained adding 12128561 to its sum of digits (26).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7480225 + 4648336 = 2735^2 + 2156^2 .

It is a cyclic number.

It is not a de Polignac number, because 12128561 - 2¹⁸ = 11866417 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 12128561.

It is not a weakly prime, because it can be changed into another prime (12128591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6064280 + 6064281.

It is an arithmetic number, because the mean of its divisors is an integer number (6064281).

Almost surely, 2^12128561 is an apocalyptic number.

It is an amenable number.

12128561 is a deficient number, since it is larger than the sum of its proper divisors (1).

12128561 is an equidigital number, since it uses as much as digits as its factorization.

12128561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 26.

The square root of 12128561 is about 3482.6083615589. The cubic root of 12128561 is about 229.7575327593.

It can be divided in two parts, 121 and 28561, that multiplied together give a square (3455881 = 1859²).

The spelling of 12128561 in words is "twelve million, one hundred twenty-eight thousand, five hundred sixty-one".