18216011993 has 2 divisors, whose sum is σ = 18216011994. Its totient is φ = 18216011992.

The previous prime is 18216011969. The next prime is 18216012047. The reversal of 18216011993 is 39911061281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16654418704 + 1561593289 = 129052^2 + 39517^2 .

It is a cyclic number.

It is not a de Polignac number, because 18216011993 - 2¹² = 18216007897 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18216011993.

It is not a weakly prime, because it can be changed into another prime (18216011923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9108005996 + 9108005997.

It is an arithmetic number, because the mean of its divisors is an integer number (9108005997).

Almost surely, 2^18216011993 is an apocalyptic number.

It is an amenable number.

18216011993 is a deficient number, since it is larger than the sum of its proper divisors (1).

18216011993 is an equidigital number, since it uses as much as digits as its factorization.

18216011993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 41.

The spelling of 18216011993 in words is "eighteen billion, two hundred sixteen million, eleven thousand, nine hundred ninety-three".