216821440 has 112 divisors (see below), whose sum is σ = 581704704. Its totient is φ = 76262400.

The previous prime is 216821413. The next prime is 216821441. The reversal of 216821440 is 44128612.

216821440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 216821399 and 216821408.

It is not an unprimeable number, because it can be changed into a prime (216821441) 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, 108127 + ... + 110113.

It is an arithmetic number, because the mean of its divisors is an integer number (5193792).

Almost surely, 2^216821440 is an apocalyptic number.

216821440 is a gapful number since it is divisible by the number (20) 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 216821440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (290852352).

216821440 is an abundant number, since it is smaller than the sum of its proper divisors (364883264).

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

216821440 is a wasteful number, since it uses less digits than its factorization.

216821440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2046 (or 2036 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 28.

The square root of 216821440 is about 14724.8578940511. The cubic root of 216821440 is about 600.7596304560.

The spelling of 216821440 in words is "two hundred sixteen million, eight hundred twenty-one thousand, four hundred forty".