166685609 has 4 divisors (see below), whose sum is σ = 166711680. Its totient is φ = 166659540.

The previous prime is 166685599. The next prime is 166685627. The reversal of 166685609 is 906586661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 166685609 - 2²⁰ = 165637033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166685639) 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, 3824 + ... + 18654.

It is an arithmetic number, because the mean of its divisors is an integer number (41677920).

Almost surely, 2^166685609 is an apocalyptic number.

It is an amenable number.

166685609 is a deficient number, since it is larger than the sum of its proper divisors (26071).

166685609 is a wasteful number, since it uses less digits than its factorization.

166685609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26070.

The product of its (nonzero) digits is 466560, while the sum is 47.

The square root of 166685609 is about 12910.6780999295. The cubic root of 166685609 is about 550.3420560948.

The spelling of 166685609 in words is "one hundred sixty-six million, six hundred eighty-five thousand, six hundred nine".