18271218991 has 4 divisors (see below), whose sum is σ = 18860613184. Its totient is φ = 17681824800.

The previous prime is 18271218989. The next prime is 18271218997. The reversal of 18271218991 is 19981217281.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18271218991 - 2¹ = 18271218989 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 (18271218997) 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, 294697050 + ... + 294697111.

It is an arithmetic number, because the mean of its divisors is an integer number (4715153296).

Almost surely, 2^18271218991 is an apocalyptic number.

18271218991 is a deficient number, since it is larger than the sum of its proper divisors (589394193).

18271218991 is an equidigital number, since it uses as much as digits as its factorization.

18271218991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 589394192.

The product of its digits is 145152, while the sum is 49.

The spelling of 18271218991 in words is "eighteen billion, two hundred seventy-one million, two hundred eighteen thousand, nine hundred ninety-one".