18281820 has 48 divisors (see below), whose sum is σ = 52164000. Its totient is φ = 4782336.

The previous prime is 18281801. The next prime is 18281831. The reversal of 18281820 is 2818281.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 306 + ... + 6054.

It is an arithmetic number, because the mean of its divisors is an integer number (1086750).

Almost surely, 2^18281820 is an apocalyptic number.

18281820 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 18281820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26082000).

18281820 is an abundant number, since it is smaller than the sum of its proper divisors (33882180).

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

18281820 is a wasteful number, since it uses less digits than its factorization.

18281820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5814 (or 5812 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 30.

The square root of 18281820 is about 4275.7245000117. The cubic root of 18281820 is about 263.4347986211.

The spelling of 18281820 in words is "eighteen million, two hundred eighty-one thousand, eight hundred twenty".