18278369 has 2 divisors, whose sum is σ = 18278370. Its totient is φ = 18278368.

The previous prime is 18278357. The next prime is 18278371. The reversal of 18278369 is 96387281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14326225 + 3952144 = 3785^2 + 1988^2 .

It is an emirp because it is prime and its reverse (96387281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18278369 - 2¹⁶ = 18212833 is a prime.

It is a super-2 number, since 2×18278369² = 668197546600322, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 18278371, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18278669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9139184 + 9139185.

It is an arithmetic number, because the mean of its divisors is an integer number (9139185).

Almost surely, 2^18278369 is an apocalyptic number.

It is an amenable number.

18278369 is a deficient number, since it is larger than the sum of its proper divisors (1).

18278369 is an equidigital number, since it uses as much as digits as its factorization.

18278369 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 44.

The square root of 18278369 is about 4275.3209236267. The cubic root of 18278369 is about 263.4182216666.

The spelling of 18278369 in words is "eighteen million, two hundred seventy-eight thousand, three hundred sixty-nine".