18236747221 has 8 divisors (see below), whose sum is σ = 22736723904. Its totient is φ = 14210452320.

The previous prime is 18236747189. The next prime is 18236747231. The reversal of 18236747221 is 12274763281.

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 18236747221 - 2⁵ = 18236747189 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 (18236747231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 118420360 + ... + 118420513.

It is an arithmetic number, because the mean of its divisors is an integer number (2842090488).

Almost surely, 2^18236747221 is an apocalyptic number.

18236747221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18236747221 is a deficient number, since it is larger than the sum of its proper divisors (4499976683).

18236747221 is a wasteful number, since it uses less digits than its factorization.

18236747221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236840891.

The product of its digits is 225792, while the sum is 43.

The spelling of 18236747221 in words is "eighteen billion, two hundred thirty-six million, seven hundred forty-seven thousand, two hundred twenty-one".