1821808 has 20 divisors (see below), whose sum is σ = 3644608. Its totient is φ = 881280.

The previous prime is 1821791. The next prime is 1821821. The reversal of 1821808 is 8081281.

1821808 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1341 + ... + 2332.

2^1821808 is an apocalyptic number.

It is an amenable number.

1821808 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

1821808 is a wasteful number, since it uses less digits than its factorization.

1821808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3712 (or 3706 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 28.

The square root of 1821808 is about 1349.7436793703. The cubic root of 1821808 is about 122.1333308967.

The spelling of 1821808 in words is "one million, eight hundred twenty-one thousand, eight hundred eight".