66642166121 has 2 divisors, whose sum is σ = 66642166122. Its totient is φ = 66642166120.

The previous prime is 66642166111. The next prime is 66642166139. The reversal of 66642166121 is 12166124666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55264957225 + 11377208896 = 235085^2 + 106664^2 .

It is a cyclic number.

It is not a de Polignac number, because 66642166121 - 2⁶ = 66642166057 is a prime.

It is not a weakly prime, because it can be changed into another prime (66642166111) 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, 33321083060 + 33321083061.

It is an arithmetic number, because the mean of its divisors is an integer number (33321083061).

Almost surely, 2^66642166121 is an apocalyptic number.

It is an amenable number.

66642166121 is a deficient number, since it is larger than the sum of its proper divisors (1).

66642166121 is an equidigital number, since it uses as much as digits as its factorization.

66642166121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 41.

The spelling of 66642166121 in words is "sixty-six billion, six hundred forty-two million, one hundred sixty-six thousand, one hundred twenty-one".