18327707821 has 4 divisors (see below), whose sum is σ = 18385524252. Its totient is φ = 18269891392.

The previous prime is 18327707773. The next prime is 18327707861. The reversal of 18327707821 is 12870772381.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1928088100 + 16399619721 = 43910^2 + 128061^2 .

It is a cyclic number.

It is not a de Polignac number, because 18327707821 - 2⁹ = 18327707309 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 (18327707861) 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, 28907740 + ... + 28908373.

It is an arithmetic number, because the mean of its divisors is an integer number (4596381063).

Almost surely, 2^18327707821 is an apocalyptic number.

It is an amenable number.

18327707821 is a deficient number, since it is larger than the sum of its proper divisors (57816431).

18327707821 is an equidigital number, since it uses as much as digits as its factorization.

18327707821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57816430.

The product of its (nonzero) digits is 263424, while the sum is 46.

The spelling of 18327707821 in words is "eighteen billion, three hundred twenty-seven million, seven hundred seven thousand, eight hundred twenty-one".