166520771777 has 2 divisors, whose sum is σ = 166520771778. Its totient is φ = 166520771776.

The previous prime is 166520771759. The next prime is 166520771779. The reversal of 166520771777 is 777177025661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 161386189441 + 5134582336 = 401729^2 + 71656^2 .

It is a cyclic number.

It is not a de Polignac number, because 166520771777 - 2⁶ = 166520771713 is a prime.

Together with 166520771779, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (166520771779) 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, 83260385888 + 83260385889.

It is an arithmetic number, because the mean of its divisors is an integer number (83260385889).

Almost surely, 2^166520771777 is an apocalyptic number.

It is an amenable number.

166520771777 is a deficient number, since it is larger than the sum of its proper divisors (1).

166520771777 is an equidigital number, since it uses as much as digits as its factorization.

166520771777 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6050520, while the sum is 56.

The spelling of 166520771777 in words is "one hundred sixty-six billion, five hundred twenty million, seven hundred seventy-one thousand, seven hundred seventy-seven".