166721885 has 16 divisors (see below), whose sum is σ = 218574720. Its totient is φ = 121074240.

The previous prime is 166721881. The next prime is 166721909. The reversal of 166721885 is 588127661.

It is a happy number.

It is not a de Polignac number, because 166721885 - 2² = 166721881 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166721881) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44339 + ... + 47951.

It is an arithmetic number, because the mean of its divisors is an integer number (13660920).

Almost surely, 2^166721885 is an apocalyptic number.

It is an amenable number.

166721885 is a deficient number, since it is larger than the sum of its proper divisors (51852835).

166721885 is a wasteful number, since it uses less digits than its factorization.

166721885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4468.

The product of its digits is 161280, while the sum is 44.

The square root of 166721885 is about 12912.0829071068. The cubic root of 166721885 is about 550.3819770783.

The spelling of 166721885 in words is "one hundred sixty-six million, seven hundred twenty-one thousand, eight hundred eighty-five".