1821636 has 48 divisors (see below), whose sum is σ = 4798080. Its totient is φ = 597600.

The previous prime is 1821613. The next prime is 1821641. The reversal of 1821636 is 6361281.

1821636 is a `hidden beast` number, since 1 + 8 + 21 + 636 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 10825 + ... + 10991.

It is an arithmetic number, because the mean of its divisors is an integer number (99960).

2^1821636 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1821636, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2399040).

1821636 is an abundant number, since it is smaller than the sum of its proper divisors (2976444).

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

1821636 is a wasteful number, since it uses less digits than its factorization.

1821636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281 (or 273 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 1821636 is about 1349.6799620651. The cubic root of 1821636 is about 122.1294871704.

The spelling of 1821636 in words is "one million, eight hundred twenty-one thousand, six hundred thirty-six".