18027921 has 4 divisors (see below), whose sum is σ = 24037232. Its totient is φ = 12018612.

The previous prime is 18027899. The next prime is 18027943. The reversal of 18027921 is 12972081.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12972081 = 3 ⋅4324027.

It is an interprime number because it is at equal distance from previous prime (18027899) and next prime (18027943).

It is not a de Polignac number, because 18027921 - 2¹⁷ = 17896849 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18027521) 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, 3004651 + ... + 3004656.

It is an arithmetic number, because the mean of its divisors is an integer number (6009308).

Almost surely, 2^18027921 is an apocalyptic number.

It is an amenable number.

18027921 is a deficient number, since it is larger than the sum of its proper divisors (6009311).

18027921 is an equidigital number, since it uses as much as digits as its factorization.

18027921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6009310.

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 18027921 is about 4245.9299334775. The cubic root of 18027921 is about 262.2095763064.

It can be divided in two parts, 180279 and 21, that added together give a triangular number (180300 = T₆₀₀).

The spelling of 18027921 in words is "eighteen million, twenty-seven thousand, nine hundred twenty-one".