2172805 has 4 divisors (see below), whose sum is σ = 2607372. Its totient is φ = 1738240.

The previous prime is 2172803. The next prime is 2172811. The reversal of 2172805 is 5082712.

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 1555009 + 617796 = 1247^2 + 786^2 .

It is not a de Polignac number, because 2172805 - 2¹ = 2172803 is a prime.

It is a super-4 number, since 4×2172805⁴ (a number of 26 digits) contains 4444 as substring.

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 2172805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2172803) 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, 217276 + ... + 217285.

It is an arithmetic number, because the mean of its divisors is an integer number (651843).

2^2172805 is an apocalyptic number.

It is an amenable number.

2172805 is a deficient number, since it is larger than the sum of its proper divisors (434567).

2172805 is an equidigital number, since it uses as much as digits as its factorization.

2172805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434566.

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 2172805 is about 1474.0437578308. The cubic root of 2172805 is about 129.5210184376.

The spelling of 2172805 in words is "two million, one hundred seventy-two thousand, eight hundred five".