1212104666561 has 2 divisors, whose sum is σ = 1212104666562. Its totient is φ = 1212104666560.

The previous prime is 1212104666533. The next prime is 1212104666579. The reversal of 1212104666561 is 1656664012121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1074838121536 + 137266545025 = 1036744^2 + 370495^2 .

It is an emirp because it is prime and its reverse (1656664012121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1212104666561 - 2¹⁸ = 1212104404417 is a prime.

It is not a weakly prime, because it can be changed into another prime (1212104666581) 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 as a sum of consecutive naturals, namely, 606052333280 + 606052333281.

It is an arithmetic number, because the mean of its divisors is an integer number (606052333281).

Almost surely, 2^{1212104666561} is an apocalyptic number.

It is an amenable number.

1212104666561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1212104666561 is an equidigital number, since it uses as much as digits as its factorization.

1212104666561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 103680, while the sum is 41.

Adding to 1212104666561 its reverse (1656664012121), we get a palindrome (2868768678682).

The spelling of 1212104666561 in words is "one trillion, two hundred twelve billion, one hundred four million, six hundred sixty-six thousand, five hundred sixty-one".