2170809 has 12 divisors (see below), whose sum is σ = 3272256. Its totient is φ = 1384152.

The previous prime is 2170783. The next prime is 2170813. The reversal of 2170809 is 9080712.

It is not a de Polignac number, because 2170809 - 2⁷ = 2170681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2170829) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5037 + ... + 5450.

It is an arithmetic number, because the mean of its divisors is an integer number (272688).

2^2170809 is an apocalyptic number.

It is an amenable number.

2170809 is a deficient number, since it is larger than the sum of its proper divisors (1101447).

2170809 is a wasteful number, since it uses less digits than its factorization.

2170809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10516 (or 10513 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 2170809 is about 1473.3665531700. The cubic root of 2170809 is about 129.4813457326.

Subtracting 2170809 from its reverse (9080712), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 2170809 in words is "two million, one hundred seventy thousand, eight hundred nine".