18021533 has 4 divisors (see below), whose sum is σ = 18207420. Its totient is φ = 17835648.

The previous prime is 18021529. The next prime is 18021569. The reversal of 18021533 is 33512081.

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 9972964 + 8048569 = 3158^2 + 2837^2 .

It is a cyclic number.

It is not a de Polignac number, because 18021533 - 2² = 18021529 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18021499 and 18021508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18021503) 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, 92798 + ... + 92991.

It is an arithmetic number, because the mean of its divisors is an integer number (4551855).

Almost surely, 2^18021533 is an apocalyptic number.

It is an amenable number.

18021533 is a deficient number, since it is larger than the sum of its proper divisors (185887).

18021533 is an equidigital number, since it uses as much as digits as its factorization.

18021533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185886.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 18021533 is about 4245.1776170144. The cubic root of 18021533 is about 262.1786022661.

The spelling of 18021533 in words is "eighteen million, twenty-one thousand, five hundred thirty-three".