18213840 has 120 divisors (see below), whose sum is σ = 62761608. Its totient is φ = 4730880.

The previous prime is 18213829. The next prime is 18213857. The reversal of 18213840 is 4831281.

It can be written as a sum of positive squares in 4 ways, for example, as 1272384 + 16941456 = 1128^2 + 4116^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 29212 + ... + 29828.

Almost surely, 2^18213840 is an apocalyptic number.

18213840 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 18213840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31380804).

18213840 is an abundant number, since it is smaller than the sum of its proper divisors (44547768).

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

18213840 is a wasteful number, since it uses less digits than its factorization.

18213840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677 (or 668 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 18213840 is about 4267.7675663044. The cubic root of 18213840 is about 263.1078701825.

The spelling of 18213840 in words is "eighteen million, two hundred thirteen thousand, eight hundred forty".