661993142089 has 2 divisors, whose sum is σ = 661993142090. Its totient is φ = 661993142088.

The previous prime is 661993142081. The next prime is 661993142117. The reversal of 661993142089 is 980241399166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 503184516025 + 158808626064 = 709355^2 + 398508^2 .

It is a cyclic number.

It is not a de Polignac number, because 661993142089 - 2³ = 661993142081 is a prime.

It is not a weakly prime, because it can be changed into another prime (661993142081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330996571044 + 330996571045.

It is an arithmetic number, because the mean of its divisors is an integer number (330996571045).

Almost surely, 2^661993142089 is an apocalyptic number.

It is an amenable number.

661993142089 is a deficient number, since it is larger than the sum of its proper divisors (1).

661993142089 is an equidigital number, since it uses as much as digits as its factorization.

661993142089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5038848, while the sum is 58.

The spelling of 661993142089 in words is "six hundred sixty-one billion, nine hundred ninety-three million, one hundred forty-two thousand, eighty-nine".