18221663641 has 8 divisors (see below), whose sum is σ = 18851966280. Its totient is φ = 17591492352.

The previous prime is 18221663591. The next prime is 18221663657. The reversal of 18221663641 is 14636612281.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1144401241 + 17077262400 = 33829^2 + 130680^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18221663641 - 2¹¹ = 18221661593 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18221663594 and 18221663603.

It is not an unprimeable number, because it can be changed into a prime (18221663041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 310351 + ... + 364363.

It is an arithmetic number, because the mean of its divisors is an integer number (2356495785).

Almost surely, 2^18221663641 is an apocalyptic number.

It is an amenable number.

18221663641 is a deficient number, since it is larger than the sum of its proper divisors (630302639).

18221663641 is a wasteful number, since it uses less digits than its factorization.

18221663641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65675.

The product of its digits is 82944, while the sum is 40.

The spelling of 18221663641 in words is "eighteen billion, two hundred twenty-one million, six hundred sixty-three thousand, six hundred forty-one".