18021235 has 4 divisors (see below), whose sum is σ = 21625488. Its totient is φ = 14416984.

The previous prime is 18021233. The next prime is 18021239. The reversal of 18021235 is 53212081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 53212081 = 13 ⋅4093237.

It is a cyclic number.

It is not a de Polignac number, because 18021235 - 2¹ = 18021233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18021233) 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, 1802119 + ... + 1802128.

It is an arithmetic number, because the mean of its divisors is an integer number (5406372).

Almost surely, 2^18021235 is an apocalyptic number.

18021235 is a deficient number, since it is larger than the sum of its proper divisors (3604253).

18021235 is an equidigital number, since it uses as much as digits as its factorization.

18021235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3604252.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 18021235 is about 4245.1425182201. The cubic root of 18021235 is about 262.1771571495.

The spelling of 18021235 in words is "eighteen million, twenty-one thousand, two hundred thirty-five".