18920819993 has 2 divisors, whose sum is σ = 18920819994. Its totient is φ = 18920819992.

The previous prime is 18920819971. The next prime is 18920820031. The reversal of 18920819993 is 39991802981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18920552704 + 267289 = 137552^2 + 517^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18920819993 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18920819923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9460409996 + 9460409997.

It is an arithmetic number, because the mean of its divisors is an integer number (9460409997).

Almost surely, 2^18920819993 is an apocalyptic number.

It is an amenable number.

18920819993 is a deficient number, since it is larger than the sum of its proper divisors (1).

18920819993 is an equidigital number, since it uses as much as digits as its factorization.

18920819993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2519424, while the sum is 59.

The spelling of 18920819993 in words is "eighteen billion, nine hundred twenty million, eight hundred nineteen thousand, nine hundred ninety-three".