18213816 has 64 divisors (see below), whose sum is σ = 47393280. Its totient is φ = 5829120.

The previous prime is 18213803. The next prime is 18213823. The reversal of 18213816 is 61831281.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

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, 75456 + ... + 75696.

It is an arithmetic number, because the mean of its divisors is an integer number (740520).

Almost surely, 2^18213816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18213816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23696640).

18213816 is an abundant number, since it is smaller than the sum of its proper divisors (29179464).

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

18213816 is a wasteful number, since it uses less digits than its factorization.

18213816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364 (or 360 counting only the distinct ones).

The product of its digits is 2304, while the sum is 30.

The square root of 18213816 is about 4267.7647545290. The cubic root of 18213816 is about 263.1077546185.

The spelling of 18213816 in words is "eighteen million, two hundred thirteen thousand, eight hundred sixteen".