1821231216 has 400 divisors, whose sum is σ = 6535742400. Its totient is φ = 487710720.

The previous prime is 1821231211. The next prime is 1821231221. The reversal of 1821231216 is 6121321281.

It is an interprime number because it is at equal distance from previous prime (1821231211) and next prime (1821231221).

It is a super-3 number, since 3×1821231216³ (a number of 29 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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

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

It is a self number, because there is not a number n which added to its sum of digits gives 1821231216.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1821231211) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 7556856 + ... + 7557096.

It is an arithmetic number, because the mean of its divisors is an integer number (16339356).

Almost surely, 2^1821231216 is an apocalyptic number.

1821231216 is a gapful number since it is divisible by the number (16) 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 1821231216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3267871200).

1821231216 is an abundant number, since it is smaller than the sum of its proper divisors (4714511184).

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

1821231216 is a wasteful number, since it uses less digits than its factorization.

1821231216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299 (or 270 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 1821231216 is about 42675.8856498609. The cubic root of 1821231216 is about 1221.2044040797.

Adding to 1821231216 its reverse (6121321281), we get a palindrome (7942552497).

The spelling of 1821231216 in words is "one billion, eight hundred twenty-one million, two hundred thirty-one thousand, two hundred sixteen".