166665601 has 2 divisors, whose sum is σ = 166665602. Its totient is φ = 166665600.

The previous prime is 166665593. The next prime is 166665683. The reversal of 166665601 is 106566661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165791376 + 874225 = 12876^2 + 935^2 .

It is an emirp because it is prime and its reverse (106566661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166665601 - 2³ = 166665593 is a prime.

It is not a weakly prime, because it can be changed into another prime (166645601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83332800 + 83332801.

It is an arithmetic number, because the mean of its divisors is an integer number (83332801).

Almost surely, 2^166665601 is an apocalyptic number.

It is an amenable number.

166665601 is a deficient number, since it is larger than the sum of its proper divisors (1).

166665601 is an equidigital number, since it uses as much as digits as its factorization.

166665601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 166665601 is about 12909.9032141996. The cubic root of 166665601 is about 550.3200352287.

The spelling of 166665601 in words is "one hundred sixty-six million, six hundred sixty-five thousand, six hundred one".