1821861816 has 96 divisors (see below), whose sum is σ = 4962854400. Its totient is φ = 555215040.

The previous prime is 1821861791. The next prime is 1821861817. The reversal of 1821861816 is 6181681281.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821861817) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5074645 + ... + 5075003.

It is an arithmetic number, because the mean of its divisors is an integer number (51696400).

Almost surely, 2^1821861816 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 1821861816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2481427200).

1821861816 is an abundant number, since it is smaller than the sum of its proper divisors (3140992584).

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

1821861816 is a wasteful number, since it uses less digits than its factorization.

1821861816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777 (or 414 counting only the distinct ones).

The product of its digits is 36864, while the sum is 42.

The square root of 1821861816 is about 42683.2732577997. The cubic root of 1821861816 is about 1221.3453348643.

The spelling of 1821861816 in words is "one billion, eight hundred twenty-one million, eight hundred sixty-one thousand, eight hundred sixteen".