1218920189 has 2 divisors, whose sum is σ = 1218920190. Its totient is φ = 1218920188.

The previous prime is 1218920159. The next prime is 1218920207. The reversal of 1218920189 is 9810298121.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1215916900 + 3003289 = 34870^2 + 1733^2 .

It is a cyclic number.

It is not a de Polignac number, because 1218920189 - 2¹⁶ = 1218854653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1218920159) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 609460094 + 609460095.

It is an arithmetic number, because the mean of its divisors is an integer number (609460095).

Almost surely, 2^1218920189 is an apocalyptic number.

It is an amenable number.

1218920189 is a deficient number, since it is larger than the sum of its proper divisors (1).

1218920189 is an equidigital number, since it uses as much as digits as its factorization.

1218920189 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 41.

The square root of 1218920189 is about 34913.0375218198. The cubic root of 1218920189 is about 1068.2143884186.

The spelling of 1218920189 in words is "one billion, two hundred eighteen million, nine hundred twenty thousand, one hundred eighty-nine".