166001666 has 4 divisors (see below), whose sum is σ = 249002502. Its totient is φ = 83000832.

The previous prime is 166001663. The next prime is 166001669. The reversal of 166001666 is 666100661.

166001666 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 666100661 = 53 ⋅12567937.

It is an interprime number because it is at equal distance from previous prime (166001663) and next prime (166001669).

It can be written as a sum of positive squares in only one way, i.e., 139736041 + 26265625 = 11821^2 + 5125^2 .

It is a super-2 number, since 2×166001666² = 55113106229551112, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (166001663) 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, 41500415 + ... + 41500418.

Almost surely, 2^166001666 is an apocalyptic number.

166001666 is a deficient number, since it is larger than the sum of its proper divisors (83000836).

166001666 is an equidigital number, since it uses as much as digits as its factorization.

166001666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83000835.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 166001666 is about 12884.1633799017. The cubic root of 166001666 is about 549.5883045798.

The spelling of 166001666 in words is "one hundred sixty-six million, one thousand, six hundred sixty-six".