172309 has 4 divisors (see below), whose sum is σ = 177004. Its totient is φ = 167616.

The previous prime is 172307. The next prime is 172313. The reversal of 172309 is 903271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 903271 = 41 ⋅22031.

It can be written as a sum of positive squares in 2 ways, for example, as 88209 + 84100 = 297^2 + 290^2 .

It is a cyclic number.

It is not a de Polignac number, because 172309 - 2¹ = 172307 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 172309.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2292 + ... + 2365.

It is an arithmetic number, because the mean of its divisors is an integer number (44251).

2¹⁷²³⁰⁹ is an apocalyptic number.

It is an amenable number.

172309 is a deficient number, since it is larger than the sum of its proper divisors (4695).

172309 is an equidigital number, since it uses as much as digits as its factorization.

172309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4694.

The product of its (nonzero) digits is 378, while the sum is 22.

The square root of 172309 is about 415.1011924820. The cubic root of 172309 is about 55.6462608623.

The spelling of 172309 in words is "one hundred seventy-two thousand, three hundred nine".