1821204 has 120 divisors (see below), whose sum is σ = 6017088. Its totient is φ = 466560.

The previous prime is 1821191. The next prime is 1821233. The reversal of 1821204 is 4021281.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 24912 + ... + 24984.

2^1821204 is an apocalyptic number.

1821204 is a gapful number since it is divisible by the number (14) 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 1821204, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3008544).

1821204 is an abundant number, since it is smaller than the sum of its proper divisors (4195884).

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

1821204 is a wasteful number, since it uses less digits than its factorization.

1821204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 1821204 is about 1349.5199146363. The cubic root of 1821204 is about 122.1198320930.

Subtracting from 1821204 its sum of digits (18), we obtain a triangular number (1821186 = T₁₉₀₈).

Adding to 1821204 its reverse (4021281), we get a palindrome (5842485).

It can be divided in two parts, 1821 and 204, that added together give a square (2025 = 45²).

The spelling of 1821204 in words is "one million, eight hundred twenty-one thousand, two hundred four".