166666663 has 4 divisors (see below), whose sum is σ = 167102208. Its totient is φ = 166231120.

The previous prime is 166666649. The next prime is 166666673. The reversal of 166666663 is 366666661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 366666661 = 9619 ⋅38119.

It is a cyclic number.

It is not a de Polignac number, because 166666663 - 2⁵ = 166666631 is a prime.

It is a super-4 number, since 4×166666663⁴ (a number of 34 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166666603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 217198 + ... + 217963.

It is an arithmetic number, because the mean of its divisors is an integer number (41775552).

Almost surely, 2^166666663 is an apocalyptic number.

166666663 is a deficient number, since it is larger than the sum of its proper divisors (435545).

166666663 is an equidigital number, since it uses as much as digits as its factorization.

166666663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435544.

The product of its digits is 839808, while the sum is 46.

The square root of 166666663 is about 12909.9443453487. The cubic root of 166666663 is about 550.3212041134.

The spelling of 166666663 in words is "one hundred sixty-six million, six hundred sixty-six thousand, six hundred sixty-three".