166172609 has 4 divisors (see below), whose sum is σ = 166198404. Its totient is φ = 166146816.

The previous prime is 166172599. The next prime is 166172621. The reversal of 166172609 is 906271661.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 30217009 + 135955600 = 5497^2 + 11660^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166172609 is a prime.

It is a super-2 number, since 2×166172609² = 55226671963733762, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (166172009) 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, 5849 + ... + 19145.

It is an arithmetic number, because the mean of its divisors is an integer number (41549601).

Almost surely, 2^166172609 is an apocalyptic number.

It is an amenable number.

166172609 is a deficient number, since it is larger than the sum of its proper divisors (25795).

166172609 is a wasteful number, since it uses less digits than its factorization.

166172609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25794.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 166172609 is about 12890.7955146298. The cubic root of 166172609 is about 549.7768891203.

The spelling of 166172609 in words is "one hundred sixty-six million, one hundred seventy-two thousand, six hundred nine".