1821599620 has 48 divisors (see below), whose sum is σ = 3978016560. Its totient is φ = 699826176.

The previous prime is 1821599603. The next prime is 1821599627. The reversal of 1821599620 is 269951281.

It can be written as a sum of positive squares in 8 ways, for example, as 19766916 + 1801832704 = 4446^2 + 42448^2 .

It is not an unprimeable number, because it can be changed into a prime (1821599627) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 103804 + ... + 120076.

It is an arithmetic number, because the mean of its divisors is an integer number (82875345).

Almost surely, 2^1821599620 is an apocalyptic number.

1821599620 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 1821599620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1989008280).

1821599620 is an abundant number, since it is smaller than the sum of its proper divisors (2156416940).

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

1821599620 is a wasteful number, since it uses less digits than its factorization.

1821599620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16504 (or 16502 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 43.

The square root of 1821599620 is about 42680.2017333564. The cubic root of 1821599620 is about 1221.2867414661.

The spelling of 1821599620 in words is "one billion, eight hundred twenty-one million, five hundred ninety-nine thousand, six hundred twenty".