2181009 has 4 divisors (see below), whose sum is σ = 2908016. Its totient is φ = 1454004.

The previous prime is 2181007. The next prime is 2181017. The reversal of 2181009 is 9001812.

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 not a de Polignac number, because 2181009 - 2¹ = 2181007 is a prime.

It is a D-number.

It is a Duffinian number.

2181009 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (2181007) 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, 363499 + ... + 363504.

It is an arithmetic number, because the mean of its divisors is an integer number (727004).

2^2181009 is an apocalyptic number.

It is an amenable number.

2181009 is a deficient number, since it is larger than the sum of its proper divisors (727007).

2181009 is an equidigital number, since it uses as much as digits as its factorization.

2181009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 727006.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 2181009 is about 1476.8239570104. The cubic root of 2181009 is about 129.6838273214.

The spelling of 2181009 in words is "two million, one hundred eighty-one thousand, nine".