166501609 has 4 divisors (see below), whose sum is σ = 166576516. Its totient is φ = 166426704.

The previous prime is 166501607. The next prime is 166501613. The reversal of 166501609 is 906105661.

166501609 is nontrivially palindromic in base 16.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 906105661 = 17 ⋅53300333.

It can be written as a sum of positive squares in 2 ways, for example, as 91298025 + 75203584 = 9555^2 + 8672^2 .

It is a cyclic number.

It is not a de Polignac number, because 166501609 - 2¹ = 166501607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166501607) 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, 34014 + ... + 38599.

It is an arithmetic number, because the mean of its divisors is an integer number (41644129).

Almost surely, 2^166501609 is an apocalyptic number.

It is an amenable number.

166501609 is a deficient number, since it is larger than the sum of its proper divisors (74907).

166501609 is an equidigital number, since it uses as much as digits as its factorization.

166501609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74906.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 166501609 is about 12903.5502478969. The cubic root of 166501609 is about 550.1394786751.

The spelling of 166501609 in words is "one hundred sixty-six million, five hundred one thousand, six hundred nine".