18217447847 has 4 divisors (see below), whose sum is σ = 18276788376. Its totient is φ = 18158107320.

The previous prime is 18217447813. The next prime is 18217447849. The reversal of 18217447847 is 74874471281.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74874471281 = 433 ⋅172920257.

It is a cyclic number.

It is not a de Polignac number, because 18217447847 - 2⁶ = 18217447783 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 (18217447849) 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, 29669804 + ... + 29670417.

It is an arithmetic number, because the mean of its divisors is an integer number (4569197094).

Almost surely, 2^18217447847 is an apocalyptic number.

18217447847 is a deficient number, since it is larger than the sum of its proper divisors (59340529).

18217447847 is an equidigital number, since it uses as much as digits as its factorization.

18217447847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59340528.

The product of its digits is 2809856, while the sum is 53.

The spelling of 18217447847 in words is "eighteen billion, two hundred seventeen million, four hundred forty-seven thousand, eight hundred forty-seven".