166115021 has 2 divisors, whose sum is σ = 166115022. Its totient is φ = 166115020.

The previous prime is 166115011. The next prime is 166115023. The reversal of 166115021 is 120511661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 149181796 + 16933225 = 12214^2 + 4115^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166115021 is a prime.

Together with 166115023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166115023) 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, 83057510 + 83057511.

It is an arithmetic number, because the mean of its divisors is an integer number (83057511).

Almost surely, 2^166115021 is an apocalyptic number.

It is an amenable number.

166115021 is a deficient number, since it is larger than the sum of its proper divisors (1).

166115021 is an equidigital number, since it uses as much as digits as its factorization.

166115021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 166115021 is about 12888.5616342554. The cubic root of 166115021 is about 549.7133724156.

Adding to 166115021 its reverse (120511661), we get a palindrome (286626682).

The spelling of 166115021 in words is "one hundred sixty-six million, one hundred fifteen thousand, twenty-one".