18081021 has 8 divisors (see below), whose sum is σ = 27552064. Its totient is φ = 10332000.

The previous prime is 18080999. The next prime is 18081023. The reversal of 18081021 is 12018081.

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

It is not a de Polignac number, because 18081021 - 2⁶ = 18080957 is a prime.

It is a super-3 number, since 3×18081021³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 861001 = 18081021 / (1 + 8 + 0 + 8 + 1 + 0 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18081023) 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, 430480 + ... + 430521.

It is an arithmetic number, because the mean of its divisors is an integer number (3444008).

Almost surely, 2^18081021 is an apocalyptic number.

It is an amenable number.

18081021 is a deficient number, since it is larger than the sum of its proper divisors (9471043).

18081021 is an equidigital number, since it uses as much as digits as its factorization.

18081021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 861011.

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 18081021 is about 4252.1783828998. The cubic root of 18081021 is about 262.4667640460.

The spelling of 18081021 in words is "eighteen million, eighty-one thousand, twenty-one".