18681391853 has 2 divisors, whose sum is σ = 18681391854. Its totient is φ = 18681391852.

The previous prime is 18681391847. The next prime is 18681391873. The reversal of 18681391853 is 35819318681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17849761609 + 831630244 = 133603^2 + 28838^2 .

It is a cyclic number.

It is not a de Polignac number, because 18681391853 - 2²² = 18677197549 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18681391795 and 18681391804.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18681391843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9340695926 + 9340695927.

It is an arithmetic number, because the mean of its divisors is an integer number (9340695927).

Almost surely, 2^18681391853 is an apocalyptic number.

It is an amenable number.

18681391853 is a deficient number, since it is larger than the sum of its proper divisors (1).

18681391853 is an equidigital number, since it uses as much as digits as its factorization.

18681391853 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 53.

The spelling of 18681391853 in words is "eighteen billion, six hundred eighty-one million, three hundred ninety-one thousand, eight hundred fifty-three".