1821000 has 64 divisors (see below), whose sum is σ = 5690880. Its totient is φ = 484800.

The previous prime is 1820999. The next prime is 1821013. The reversal of 1821000 is 1281.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (12).

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, 2697 + ... + 3303.

It is an arithmetic number, because the mean of its divisors is an integer number (88920).

2^1821000 is an apocalyptic number.

1821000 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 1821000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2845440).

1821000 is an abundant number, since it is smaller than the sum of its proper divisors (3869880).

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

1821000 is a wasteful number, since it uses less digits than its factorization.

1821000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 631 (or 617 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 1821000 is about 1349.4443300855. Note that the first 3 decimals coincide. The cubic root of 1821000 is about 122.1152722202.

Adding to 1821000 its reverse (1281), we get a palindrome (1822281).

The spelling of 1821000 in words is "one million, eight hundred twenty-one thousand".