1218780389 has 2 divisors, whose sum is σ = 1218780390. Its totient is φ = 1218780388.

The previous prime is 1218780349. The next prime is 1218780463. The reversal of 1218780389 is 9830878121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1217661025 + 1119364 = 34895^2 + 1058^2 .

It is an emirp because it is prime and its reverse (9830878121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1218780389 - 2²⁸ = 950344933 is a prime.

It is a super-2 number, since 2×1218780389² = 2970851273221982642, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1218780319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 609390194 + 609390195.

It is an arithmetic number, because the mean of its divisors is an integer number (609390195).

Almost surely, 2^1218780389 is an apocalyptic number.

It is an amenable number.

1218780389 is a deficient number, since it is larger than the sum of its proper divisors (1).

1218780389 is an equidigital number, since it uses as much as digits as its factorization.

1218780389 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 193536, while the sum is 47.

The square root of 1218780389 is about 34911.0353470074. The cubic root of 1218780389 is about 1068.1735484242.

The spelling of 1218780389 in words is "one billion, two hundred eighteen million, seven hundred eighty thousand, three hundred eighty-nine".