2181309 has 8 divisors (see below), whose sum is σ = 3132192. Its totient is φ = 1342320.

The previous prime is 2181271. The next prime is 2181329. The reversal of 2181309 is 9031812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2181309 - 2⁹ = 2180797 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181329) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27927 + ... + 28004.

It is an arithmetic number, because the mean of its divisors is an integer number (391524).

2^2181309 is an apocalyptic number.

It is an amenable number.

2181309 is a deficient number, since it is larger than the sum of its proper divisors (950883).

2181309 is a wasteful number, since it uses less digits than its factorization.

2181309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55947.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 2181309 is about 1476.9255228345. The cubic root of 2181309 is about 129.6897730961.

The spelling of 2181309 in words is "two million, one hundred eighty-one thousand, three hundred nine".