1218809 has 4 divisors (see below), whose sum is σ = 1223040. Its totient is φ = 1214580.

The previous prime is 1218787. The next prime is 1218821. The reversal of 1218809 is 9088121.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1218809 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1218829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1649 + ... + 2270.

It is an arithmetic number, because the mean of its divisors is an integer number (305760).

2^1218809 is an apocalyptic number.

It is an amenable number.

1218809 is a deficient number, since it is larger than the sum of its proper divisors (4231).

1218809 is an equidigital number, since it uses as much as digits as its factorization.

1218809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4230.

The product of its (nonzero) digits is 1152, while the sum is 29.

The square root of 1218809 is about 1103.9968297056. The cubic root of 1218809 is about 106.8181906855.

The spelling of 1218809 in words is "one million, two hundred eighteen thousand, eight hundred nine".