18778983217 has 4 divisors (see below), whose sum is σ = 18819543040. Its totient is φ = 18738423396.

The previous prime is 18778983193. The next prime is 18778983229. The reversal of 18778983217 is 71238987781.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18778983217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18778983247) 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, 20279217 + ... + 20280142.

It is an arithmetic number, because the mean of its divisors is an integer number (4704885760).

Almost surely, 2^18778983217 is an apocalyptic number.

It is an amenable number.

18778983217 is a deficient number, since it is larger than the sum of its proper divisors (40559823).

18778983217 is an equidigital number, since it uses as much as digits as its factorization.

18778983217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40559822.

The product of its digits is 9483264, while the sum is 61.

The spelling of 18778983217 in words is "eighteen billion, seven hundred seventy-eight million, nine hundred eighty-three thousand, two hundred seventeen".