661393770593 has 2 divisors, whose sum is σ = 661393770594. Its totient is φ = 661393770592.

The previous prime is 661393770533. The next prime is 661393770619. The reversal of 661393770593 is 395077393166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 661386948049 + 6822544 = 813257^2 + 2612^2 .

It is a cyclic number.

It is not a de Polignac number, because 661393770593 - 2²⁰ = 661392722017 is a prime.

It is not a weakly prime, because it can be changed into another prime (661393770533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330696885296 + 330696885297.

It is an arithmetic number, because the mean of its divisors is an integer number (330696885297).

Almost surely, 2^661393770593 is an apocalyptic number.

It is an amenable number.

661393770593 is a deficient number, since it is larger than the sum of its proper divisors (1).

661393770593 is an equidigital number, since it uses as much as digits as its factorization.

661393770593 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19289340, while the sum is 59.

The spelling of 661393770593 in words is "six hundred sixty-one billion, three hundred ninety-three million, seven hundred seventy thousand, five hundred ninety-three".