18811219681 has 2 divisors, whose sum is σ = 18811219682. Its totient is φ = 18811219680.

The previous prime is 18811219657. The next prime is 18811219733. The reversal of 18811219681 is 18691211881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13400146081 + 5411073600 = 115759^2 + 73560^2 .

It is an emirp because it is prime and its reverse (18691211881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18811219681 - 2¹⁵ = 18811186913 is a prime.

It is a super-2 number, since 2×18811219681² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18811219601) 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, 9405609840 + 9405609841.

It is an arithmetic number, because the mean of its divisors is an integer number (9405609841).

Almost surely, 2^18811219681 is an apocalyptic number.

It is an amenable number.

18811219681 is a deficient number, since it is larger than the sum of its proper divisors (1).

18811219681 is an equidigital number, since it uses as much as digits as its factorization.

18811219681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 55296, while the sum is 46.

The spelling of 18811219681 in words is "eighteen billion, eight hundred eleven million, two hundred nineteen thousand, six hundred eighty-one".