1305604615561 has 2 divisors, whose sum is σ = 1305604615562. Its totient is φ = 1305604615560.

The previous prime is 1305604615531. The next prime is 1305604615583. The reversal of 1305604615561 is 1655164065031.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 800588299536 + 505016316025 = 894756^2 + 710645^2 .

It is an emirp because it is prime and its reverse (1655164065031) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1305604615561 - 2²⁹ = 1305067744649 is a prime.

It is not a weakly prime, because it can be changed into another prime (1305604615501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 652802307780 + 652802307781.

It is an arithmetic number, because the mean of its divisors is an integer number (652802307781).

Almost surely, 2^{1305604615561} is an apocalyptic number.

It is an amenable number.

1305604615561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1305604615561 is an equidigital number, since it uses as much as digits as its factorization.

1305604615561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324000, while the sum is 43.

The spelling of 1305604615561 in words is "one trillion, three hundred five billion, six hundred four million, six hundred fifteen thousand, five hundred sixty-one".