66660161 has 2 divisors, whose sum is σ = 66660162. Its totient is φ = 66660160.

The previous prime is 66660131. The next prime is 66660163. The reversal of 66660161 is 16106666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64000000 + 2660161 = 8000^2 + 1631^2 .

It is a cyclic number.

It is not a de Polignac number, because 66660161 - 2¹⁰ = 66659137 is a prime.

It is a Sophie Germain prime.

Together with 66660163, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (66660163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33330080 + 33330081.

It is an arithmetic number, because the mean of its divisors is an integer number (33330081).

Almost surely, 2^66660161 is an apocalyptic number.

It is an amenable number.

66660161 is a deficient number, since it is larger than the sum of its proper divisors (1).

66660161 is an equidigital number, since it uses as much as digits as its factorization.

66660161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 66660161 is about 8164.5674104633. The cubic root of 66660161 is about 405.4669430162.

The spelling of 66660161 in words is "sixty-six million, six hundred sixty thousand, one hundred sixty-one".