18421440 has 112 divisors (see below), whose sum is σ = 60472320. Its totient is φ = 4746240.

The previous prime is 18421439. The next prime is 18421483. The reversal of 18421440 is 4412481.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 18421440.

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, 29451 + ... + 30069.

Almost surely, 2^18421440 is an apocalyptic number.

18421440 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 18421440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30236160).

18421440 is an abundant number, since it is smaller than the sum of its proper divisors (42050880).

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

18421440 is a wasteful number, since it uses less digits than its factorization.

18421440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 670 (or 660 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 18421440 is about 4292.0205032129. The cubic root of 18421440 is about 264.1037241639.

The spelling of 18421440 in words is "eighteen million, four hundred twenty-one thousand, four hundred forty".