166406681 has 8 divisors (see below), whose sum is σ = 191439744. Its totient is φ = 141688800.

The previous prime is 166406629. The next prime is 166406687. The reversal of 166406681 is 186604661.

It is a happy number.

166406681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 166406681 - 2²² = 162212377 is a prime.

It is a super-2 number, since 2×166406681² = 55382366962871522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166406687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77660 + ... + 79773.

It is an arithmetic number, because the mean of its divisors is an integer number (23929968).

Almost surely, 2^166406681 is an apocalyptic number.

It is an amenable number.

166406681 is a deficient number, since it is larger than the sum of its proper divisors (25033063).

166406681 is a wasteful number, since it uses less digits than its factorization.

166406681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157591.

The product of its (nonzero) digits is 41472, while the sum is 38.

The square root of 166406681 is about 12899.8713559477. The cubic root of 166406681 is about 550.0349079772.

The spelling of 166406681 in words is "one hundred sixty-six million, four hundred six thousand, six hundred eighty-one".