661335533161 has 2 divisors, whose sum is σ = 661335533162. Its totient is φ = 661335533160.

The previous prime is 661335533141. The next prime is 661335533189. The reversal of 661335533161 is 161335533166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 660196875625 + 1138657536 = 812525^2 + 33744^2 .

It is a cyclic number.

It is not a de Polignac number, because 661335533161 - 2¹¹ = 661335531113 is a prime.

It is not a weakly prime, because it can be changed into another prime (661335533141) 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, 330667766580 + 330667766581.

It is an arithmetic number, because the mean of its divisors is an integer number (330667766581).

Almost surely, 2^661335533161 is an apocalyptic number.

It is an amenable number.

661335533161 is a deficient number, since it is larger than the sum of its proper divisors (1).

661335533161 is an equidigital number, since it uses as much as digits as its factorization.

661335533161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 437400, while the sum is 43.

The spelling of 661335533161 in words is "six hundred sixty-one billion, three hundred thirty-five million, five hundred thirty-three thousand, one hundred sixty-one".