172009 has 2 divisors, whose sum is σ = 172010. Its totient is φ = 172008.

The previous prime is 172001. The next prime is 172021. The reversal of 172009 is 900271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157609 + 14400 = 397^2 + 120^2 .

It is a cyclic number.

It is not a de Polignac number, because 172009 - 2³ = 172001 is a prime.

It is not a weakly prime, because it can be changed into another prime (172001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86004 + 86005.

It is an arithmetic number, because the mean of its divisors is an integer number (86005).

2¹⁷²⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

172009 is a deficient number, since it is larger than the sum of its proper divisors (1).

172009 is an equidigital number, since it uses as much as digits as its factorization.

172009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126, while the sum is 19.

The square root of 172009 is about 414.7396773881. The cubic root of 172009 is about 55.6139476421.

It can be divided in two parts, 1 and 72009, that added together give a triangular number (72010 = T₃₇₉).

The spelling of 172009 in words is "one hundred seventy-two thousand, nine".