166666655 has 4 divisors (see below), whose sum is σ = 199999992. Its totient is φ = 133333320.

The previous prime is 166666649. The next prime is 166666673. The reversal of 166666655 is 556666661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 556666661 = 1627 ⋅342143.

It is not a de Polignac number, because 166666655 - 2⁴ = 166666639 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 16666661 + ... + 16666670.

It is an arithmetic number, because the mean of its divisors is an integer number (49999998).

Almost surely, 2^166666655 is an apocalyptic number.

166666655 is a deficient number, since it is larger than the sum of its proper divisors (33333337).

166666655 is an equidigital number, since it uses as much as digits as its factorization.

166666655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33333336.

The product of its digits is 1166400, while the sum is 47.

The square root of 166666655 is about 12909.9440355100. The cubic root of 166666655 is about 550.3211953083.

The spelling of 166666655 in words is "one hundred sixty-six million, six hundred sixty-six thousand, six hundred fifty-five".