2181409 has 16 divisors (see below), whose sum is σ = 2462400. Its totient is φ = 1923264.

The previous prime is 2181379. The next prime is 2181419. The reversal of 2181409 is 9041812.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 2181409 - 2¹¹ = 2179361 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (2181419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20334 + ... + 20440.

It is an arithmetic number, because the mean of its divisors is an integer number (153900).

2^2181409 is an apocalyptic number.

2181409 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

2181409 is a deficient number, since it is larger than the sum of its proper divisors (280991).

2181409 is a wasteful number, since it uses less digits than its factorization.

2181409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 2181409 is about 1476.9593765571. The cubic root of 2181409 is about 129.6917548998.

The spelling of 2181409 in words is "two million, one hundred eighty-one thousand, four hundred nine".