18821816 has 32 divisors (see below), whose sum is σ = 38556000. Its totient is φ = 8561280.

The previous prime is 18821779. The next prime is 18821819. The reversal of 18821816 is 61812881.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18821819) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 6110 + ... + 8658.

It is an arithmetic number, because the mean of its divisors is an integer number (1204875).

Almost surely, 2^18821816 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 18821816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19278000).

18821816 is an abundant number, since it is smaller than the sum of its proper divisors (19734184).

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

18821816 is a wasteful number, since it uses less digits than its factorization.

18821816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2639 (or 2635 counting only the distinct ones).

The product of its digits is 6144, while the sum is 35.

The square root of 18821816 is about 4338.4116909302. The cubic root of 18821816 is about 266.0033918952.

The spelling of 18821816 in words is "eighteen million, eight hundred twenty-one thousand, eight hundred sixteen".