2172909 has 4 divisors (see below), whose sum is σ = 2897216. Its totient is φ = 1448604.

The previous prime is 2172901. The next prime is 2172917. The reversal of 2172909 is 9092712.

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.

It is an interprime number because it is at equal distance from previous prime (2172901) and next prime (2172917).

It is not a de Polignac number, because 2172909 - 2³ = 2172901 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2172901) 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, 362149 + ... + 362154.

It is an arithmetic number, because the mean of its divisors is an integer number (724304).

2^2172909 is an apocalyptic number.

It is an amenable number.

2172909 is a deficient number, since it is larger than the sum of its proper divisors (724307).

2172909 is an equidigital number, since it uses as much as digits as its factorization.

2172909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 724306.

The product of its (nonzero) digits is 2268, while the sum is 30.

The square root of 2172909 is about 1474.0790345161. The cubic root of 2172909 is about 129.5230848865.

It can be divided in two parts, 2172 and 909, that added together give a triangular number (3081 = T₇₈).

The spelling of 2172909 in words is "two million, one hundred seventy-two thousand, nine hundred nine".