21332220 has 96 divisors (see below), whose sum is σ = 73532928. Its totient is φ = 4499712.

The previous prime is 21332209. The next prime is 21332221. The reversal of 21332220 is 2223312.

It is a super-2 number, since 2×21332220² = 910127220256800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21332220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21332221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3507 + ... + 7413.

It is an arithmetic number, because the mean of its divisors is an integer number (765968).

Almost surely, 2^21332220 is an apocalyptic number.

21332220 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 21332220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36766464).

21332220 is an abundant number, since it is smaller than the sum of its proper divisors (52200708).

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

21332220 is a wasteful number, since it uses less digits than its factorization.

21332220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3939 (or 3937 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21332220 is about 4618.6816300758. The cubic root of 21332220 is about 277.3396850175.

Adding to 21332220 its reverse (2223312), we get a palindrome (23555532).

The spelling of 21332220 in words is "twenty-one million, three hundred thirty-two thousand, two hundred twenty".