18021139 has 8 divisors (see below), whose sum is σ = 20085840. Its totient is φ = 16068096.

The previous prime is 18021131. The next prime is 18021187. The reversal of 18021139 is 93112081.

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 18021139 - 2³ = 18021131 is a prime.

It is a super-2 number, since 2×18021139² = 649522901714642, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18021131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27574 + ... + 28219.

It is an arithmetic number, because the mean of its divisors is an integer number (2510730).

Almost surely, 2^18021139 is an apocalyptic number.

18021139 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

18021139 is a deficient number, since it is larger than the sum of its proper divisors (2064701).

18021139 is a wasteful number, since it uses less digits than its factorization.

18021139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55829.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 18021139 is about 4245.1312111641. The cubic root of 18021139 is about 262.1766916051.

The spelling of 18021139 in words is "eighteen million, twenty-one thousand, one hundred thirty-nine".