18039641821 has 4 divisors (see below), whose sum is σ = 18044680192. Its totient is φ = 18034603452.

The previous prime is 18039641803. The next prime is 18039641839. The reversal of 18039641821 is 12814693081.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12814693081 = 503 ⋅25476527.

It is an interprime number because it is at equal distance from previous prime (18039641803) and next prime (18039641839).

It is a cyclic number.

It is not a de Polignac number, because 18039641821 - 2⁹ = 18039641309 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 (18039641801) 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, 2513811 + ... + 2520976.

It is an arithmetic number, because the mean of its divisors is an integer number (4511170048).

Almost surely, 2^18039641821 is an apocalyptic number.

It is an amenable number.

18039641821 is a deficient number, since it is larger than the sum of its proper divisors (5038371).

18039641821 is an equidigital number, since it uses as much as digits as its factorization.

18039641821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5038370.

The product of its (nonzero) digits is 82944, while the sum is 43.

The spelling of 18039641821 in words is "eighteen billion, thirty-nine million, six hundred forty-one thousand, eight hundred twenty-one".