18021240 has 96 divisors (see below), whose sum is σ = 59220720. Its totient is φ = 4752384.

The previous prime is 18021239. The next prime is 18021247. The reversal of 18021240 is 4212081.

It is a super-2 number, since 2×18021240² = 649530182275200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18021247) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 40459 + ... + 40901.

Almost surely, 2^18021240 is an apocalyptic number.

18021240 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18021240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29610360).

18021240 is an abundant number, since it is smaller than the sum of its proper divisors (41199480).

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

18021240 is a wasteful number, since it uses less digits than its factorization.

18021240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 573 (or 566 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 18021240 is about 4245.1431071284. The cubic root of 18021240 is about 262.1771813965.

The spelling of 18021240 in words is "eighteen million, twenty-one thousand, two hundred forty".