21221120 has 72 divisors (see below), whose sum is σ = 51876720. Its totient is φ = 8314880.

The previous prime is 21221113. The next prime is 21221129. The reversal of 21221120 is 2112212.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221129) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75380 + ... + 75660.

It is an arithmetic number, because the mean of its divisors is an integer number (720510).

Almost surely, 2^21221120 is an apocalyptic number.

21221120 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 21221120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25938360).

21221120 is an abundant number, since it is smaller than the sum of its proper divisors (30655600).

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

21221120 is an equidigital number, since it uses as much as digits as its factorization.

21221120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361 (or 347 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21221120 is about 4606.6386878070. The cubic root of 21221120 is about 276.8573772599.

Adding to 21221120 its reverse (2112212), we get a palindrome (23333332).

The spelling of 21221120 in words is "twenty-one million, two hundred twenty-one thousand, one hundred twenty".