166686721 has 8 divisors (see below), whose sum is σ = 172224000. Its totient is φ = 161159520.

The previous prime is 166686713. The next prime is 166686733. The reversal of 166686721 is 127686661.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 166686721 - 2³ = 166686713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166683721) 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 in 7 ways as a sum of consecutive naturals, for example, 46605 + ... + 50053.

It is an arithmetic number, because the mean of its divisors is an integer number (21528000).

Almost surely, 2^166686721 is an apocalyptic number.

It is an amenable number.

166686721 is a deficient number, since it is larger than the sum of its proper divisors (5537279).

166686721 is a wasteful number, since it uses less digits than its factorization.

166686721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5039.

The product of its digits is 145152, while the sum is 43.

The square root of 166686721 is about 12910.7211649853. The cubic root of 166686721 is about 550.3432799138.

The spelling of 166686721 in words is "one hundred sixty-six million, six hundred eighty-six thousand, seven hundred twenty-one".