166221193 has 2 divisors, whose sum is σ = 166221194. Its totient is φ = 166221192.

The previous prime is 166221191. The next prime is 166221203. The reversal of 166221193 is 391122661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 147185424 + 19035769 = 12132^2 + 4363^2 .

It is an emirp because it is prime and its reverse (391122661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166221193 - 2¹ = 166221191 is a prime.

Together with 166221191, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (166221191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83110596 + 83110597.

It is an arithmetic number, because the mean of its divisors is an integer number (83110597).

Almost surely, 2^166221193 is an apocalyptic number.

It is an amenable number.

166221193 is a deficient number, since it is larger than the sum of its proper divisors (1).

166221193 is an equidigital number, since it uses as much as digits as its factorization.

166221193 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 31.

The square root of 166221193 is about 12892.6798222868. The cubic root of 166221193 is about 549.8304634485.

The spelling of 166221193 in words is "one hundred sixty-six million, two hundred twenty-one thousand, one hundred ninety-three".