1218726909 has 6 divisors (see below), whose sum is σ = 1760383326. Its totient is φ = 812484600.

The previous prime is 1218726893. The next prime is 1218726913. The reversal of 1218726909 is 9096278121.

1218726909 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 1103701284 + 115025625 = 33222^2 + 10725^2 .

It is not a de Polignac number, because 1218726909 - 2⁴ = 1218726893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1218726989) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 67707042 + ... + 67707059.

It is an arithmetic number, because the mean of its divisors is an integer number (293397221).

Almost surely, 2^1218726909 is an apocalyptic number.

It is an amenable number.

1218726909 is a deficient number, since it is larger than the sum of its proper divisors (541656417).

1218726909 is a wasteful number, since it uses less digits than its factorization.

1218726909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135414107 (or 135414104 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The square root of 1218726909 is about 34910.2693916847. The cubic root of 1218726909 is about 1068.1579244016.

The spelling of 1218726909 in words is "one billion, two hundred eighteen million, seven hundred twenty-six thousand, nine hundred nine".