1821805820 has 12 divisors (see below), whose sum is σ = 3825792264. Its totient is φ = 728722320.

The previous prime is 1821805771. The next prime is 1821805831. The reversal of 1821805820 is 285081281.

1821805820 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45545126 + ... + 45545165.

It is an arithmetic number, because the mean of its divisors is an integer number (318816022).

Almost surely, 2^1821805820 is an apocalyptic number.

1821805820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1821805820 is an abundant number, since it is smaller than the sum of its proper divisors (2003986444).

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

1821805820 is a wasteful number, since it uses less digits than its factorization.

1821805820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91090300 (or 91090298 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 35.

The square root of 1821805820 is about 42682.6173049404. The cubic root of 1821805820 is about 1221.3328218125.

The spelling of 1821805820 in words is "one billion, eight hundred twenty-one million, eight hundred five thousand, eight hundred twenty".