18021540 has 48 divisors (see below), whose sum is σ = 52093440. Its totient is φ = 4650240.

The previous prime is 18021529. The next prime is 18021569. The reversal of 18021540 is 4512081.

It is a super-3 number, since 3×18021540³ (a number of 23 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2985 + ... + 6704.

It is an arithmetic number, because the mean of its divisors is an integer number (1085280).

Almost surely, 2^18021540 is an apocalyptic number.

18021540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18021540 is an abundant number, since it is smaller than the sum of its proper divisors (34071900).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18021540 is a wasteful number, since it uses less digits than its factorization.

18021540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9732 (or 9730 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 18021540 is about 4245.1784414792. The cubic root of 18021540 is about 262.1786362116.

The spelling of 18021540 in words is "eighteen million, twenty-one thousand, five hundred forty".