2172865 has 4 divisors (see below), whose sum is σ = 2607444. Its totient is φ = 1738288.

The previous prime is 2172853. The next prime is 2172869. The reversal of 2172865 is 5682712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 703921 + 1468944 = 839^2 + 1212^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2172865 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2172869) 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, 217282 + ... + 217291.

It is an arithmetic number, because the mean of its divisors is an integer number (651861).

2^2172865 is an apocalyptic number.

It is an amenable number.

2172865 is a deficient number, since it is larger than the sum of its proper divisors (434579).

2172865 is an equidigital number, since it uses as much as digits as its factorization.

2172865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434578.

The product of its digits is 6720, while the sum is 31.

The square root of 2172865 is about 1474.0641098677. The cubic root of 2172865 is about 129.5222106277.

The spelling of 2172865 in words is "two million, one hundred seventy-two thousand, eight hundred sixty-five".