1821656844 has 192 divisors, whose sum is σ = 5866291200. Its totient is φ = 477057600.

The previous prime is 1821656831. The next prime is 1821656849. The reversal of 1821656844 is 4486561281.

It is a happy number.

1821656844 is a `hidden beast` number, since 1 + 82 + 1 + 6 + 568 + 4 + 4 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 1821656844.

It is not an unprimeable number, because it can be changed into a prime (1821656849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 443239 + ... + 447329.

It is an arithmetic number, because the mean of its divisors is an integer number (30553600).

Almost surely, 2^1821656844 is an apocalyptic number.

1821656844 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 1821656844, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2933145600).

1821656844 is an abundant number, since it is smaller than the sum of its proper divisors (4044634356).

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

1821656844 is a wasteful number, since it uses less digits than its factorization.

1821656844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4161 (or 4153 counting only the distinct ones).

The product of its digits is 368640, while the sum is 45.

The square root of 1821656844 is about 42680.8721091779. The cubic root of 1821656844 is about 1221.2995298930.

It can be divided in two parts, 1821656 and 844, that added together give a square (1822500 = 1350²).

The spelling of 1821656844 in words is "one billion, eight hundred twenty-one million, six hundred fifty-six thousand, eight hundred forty-four".