18013820 has 48 divisors (see below), whose sum is σ = 42402528. Its totient is φ = 6370560.

The previous prime is 18013819. The next prime is 18013823. The reversal of 18013820 is 2831081.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18013823) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7034 + ... + 9246.

It is an arithmetic number, because the mean of its divisors is an integer number (883386).

Almost surely, 2^18013820 is an apocalyptic number.

18013820 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 18013820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21201264).

18013820 is an abundant number, since it is smaller than the sum of its proper divisors (24388708).

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

18013820 is a wasteful number, since it uses less digits than its factorization.

18013820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2270 (or 2268 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 18013820 is about 4244.2690772382. The cubic root of 18013820 is about 262.1411938296.

The spelling of 18013820 in words is "eighteen million, thirteen thousand, eight hundred twenty".