1218943609 has 4 divisors (see below), whose sum is σ = 1312708516. Its totient is φ = 1125178704.

The previous prime is 1218943601. The next prime is 1218943619. The reversal of 1218943609 is 9063498121.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 718079209 + 500864400 = 26797^2 + 22380^2 .

It is not a de Polignac number, because 1218943609 - 2³ = 1218943601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1218943601) 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, 46882434 + ... + 46882459.

It is an arithmetic number, because the mean of its divisors is an integer number (328177129).

Almost surely, 2^1218943609 is an apocalyptic number.

It is an amenable number.

1218943609 is a deficient number, since it is larger than the sum of its proper divisors (93764907).

1218943609 is an equidigital number, since it uses as much as digits as its factorization.

1218943609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93764906.

The product of its (nonzero) digits is 93312, while the sum is 43.

The square root of 1218943609 is about 34913.3729249982. The cubic root of 1218943609 is about 1068.2212298347.

The spelling of 1218943609 in words is "one billion, two hundred eighteen million, nine hundred forty-three thousand, six hundred nine".