18219818687 has 4 divisors (see below), whose sum is σ = 20822649936. Its totient is φ = 15616987440.

The previous prime is 18219818657. The next prime is 18219818717. The reversal of 18219818687 is 78681891281.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78681891281 = 7 ⋅11240270183.

It is an interprime number because it is at equal distance from previous prime (18219818657) and next prime (18219818717).

It is a cyclic number.

It is not a de Polignac number, because 18219818687 - 2²⁴ = 18203041471 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 (18219818627) 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, 1301415614 + ... + 1301415627.

It is an arithmetic number, because the mean of its divisors is an integer number (5205662484).

Almost surely, 2^18219818687 is an apocalyptic number.

18219818687 is a deficient number, since it is larger than the sum of its proper divisors (2602831249).

18219818687 is an equidigital number, since it uses as much as digits as its factorization.

18219818687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2602831248.

The product of its digits is 3096576, while the sum is 59.

The spelling of 18219818687 in words is "eighteen billion, two hundred nineteen million, eight hundred eighteen thousand, six hundred eighty-seven".