166021729 has 2 divisors, whose sum is σ = 166021730. Its totient is φ = 166021728.

The previous prime is 166021727. The next prime is 166021741. The reversal of 166021729 is 927120661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165071104 + 950625 = 12848^2 + 975^2 .

It is an emirp because it is prime and its reverse (927120661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166021729 - 2¹ = 166021727 is a prime.

Together with 166021727, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 166021694 and 166021703.

It is not a weakly prime, because it can be changed into another prime (166021721) 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, 83010864 + 83010865.

It is an arithmetic number, because the mean of its divisors is an integer number (83010865).

Almost surely, 2^166021729 is an apocalyptic number.

It is an amenable number.

166021729 is a deficient number, since it is larger than the sum of its proper divisors (1).

166021729 is an equidigital number, since it uses as much as digits as its factorization.

166021729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 166021729 is about 12884.9419478708. The cubic root of 166021729 is about 549.6104448113.

The spelling of 166021729 in words is "one hundred sixty-six million, twenty-one thousand, seven hundred twenty-nine".