18778841 has 2 divisors, whose sum is σ = 18778842. Its totient is φ = 18778840.

The previous prime is 18778819. The next prime is 18778843. The reversal of 18778841 is 14887781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11703241 + 7075600 = 3421^2 + 2660^2 .

It is a cyclic number.

It is not a de Polignac number, because 18778841 - 2¹⁰ = 18777817 is a prime.

It is a Sophie Germain prime.

Together with 18778843, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 18778792 and 18778801.

It is not a weakly prime, because it can be changed into another prime (18778843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9389420 + 9389421.

It is an arithmetic number, because the mean of its divisors is an integer number (9389421).

Almost surely, 2^18778841 is an apocalyptic number.

It is an amenable number.

18778841 is a deficient number, since it is larger than the sum of its proper divisors (1).

18778841 is an equidigital number, since it uses as much as digits as its factorization.

18778841 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100352, while the sum is 44.

The square root of 18778841 is about 4333.4560110840. The cubic root of 18778841 is about 265.8007864513.

The spelling of 18778841 in words is "eighteen million, seven hundred seventy-eight thousand, eight hundred forty-one".