18811219717 has 4 divisors (see below), whose sum is σ = 19270029996. Its totient is φ = 18352409440.

The previous prime is 18811219681. The next prime is 18811219733. The reversal of 18811219717 is 71791211881.

It is a Cunningham number, because it is equal to 137154²+1.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71791211881 = 43 ⋅1669563067.

It can be written as a sum of positive squares in 2 ways, for example, as 906371236 + 17904848481 = 30106^2 + 133809^2 .

It is a cyclic number.

It is not a de Polignac number, because 18811219717 - 2²⁷ = 18677001989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18811219787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 229405078 + ... + 229405159.

It is an arithmetic number, because the mean of its divisors is an integer number (4817507499).

Almost surely, 2^18811219717 is an apocalyptic number.

It is an amenable number.

18811219717 is a deficient number, since it is larger than the sum of its proper divisors (458810279).

18811219717 is an equidigital number, since it uses as much as digits as its factorization.

18811219717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458810278.

The product of its digits is 56448, while the sum is 46.

The spelling of 18811219717 in words is "eighteen billion, eight hundred eleven million, two hundred nineteen thousand, seven hundred seventeen".