1218161939 has 2 divisors, whose sum is σ = 1218161940. Its totient is φ = 1218161938.

The previous prime is 1218161899. The next prime is 1218161993. The reversal of 1218161939 is 9391618121.

Together with next prime (1218161993) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is an emirp because it is prime and its reverse (9391618121) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1218161939 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1218161896 and 1218161905.

It is not a weakly prime, because it can be changed into another prime (1218161039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 609080969 + 609080970.

It is an arithmetic number, because the mean of its divisors is an integer number (609080970).

Almost surely, 2^1218161939 is an apocalyptic number.

1218161939 is a deficient number, since it is larger than the sum of its proper divisors (1).

1218161939 is an equidigital number, since it uses as much as digits as its factorization.

1218161939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 41.

The square root of 1218161939 is about 34902.1767086238. The cubic root of 1218161939 is about 1067.9928421741.

The spelling of 1218161939 in words is "one billion, two hundred eighteen million, one hundred sixty-one thousand, nine hundred thirty-nine".