18778063861 has 2 divisors, whose sum is σ = 18778063862. Its totient is φ = 18778063860.

The previous prime is 18778063853. The next prime is 18778063867. The reversal of 18778063861 is 16836087781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12747764836 + 6030299025 = 112906^2 + 77655^2 .

It is an emirp because it is prime and its reverse (16836087781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18778063861 - 2³ = 18778063853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18778063867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9389031930 + 9389031931.

It is an arithmetic number, because the mean of its divisors is an integer number (9389031931).

Almost surely, 2^18778063861 is an apocalyptic number.

It is an amenable number.

18778063861 is a deficient number, since it is larger than the sum of its proper divisors (1).

18778063861 is an equidigital number, since it uses as much as digits as its factorization.

18778063861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2709504, while the sum is 55.

The spelling of 18778063861 in words is "eighteen billion, seven hundred seventy-eight million, sixty-three thousand, eight hundred sixty-one".