21443220 has 36 divisors (see below), whose sum is σ = 65044980. Its totient is φ = 5718144.

The previous prime is 21443203. The next prime is 21443221. The reversal of 21443220 is 2234412.

21443220 is a `hidden beast` number, since 2 + 1 + 443 + 220 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 3090564 + 18352656 = 1758^2 + 4284^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a plaindrome in base 11.

It is a zygodrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21443193 and 21443202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21443221) 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 11 ways as a sum of consecutive naturals, for example, 59385 + ... + 59744.

It is an arithmetic number, because the mean of its divisors is an integer number (1806805).

Almost surely, 2^21443220 is an apocalyptic number.

21443220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21443220 is an abundant number, since it is smaller than the sum of its proper divisors (43601760).

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

21443220 is a wasteful number, since it uses less digits than its factorization.

21443220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119144 (or 119139 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21443220 is about 4630.6824551031. The cubic root of 21443220 is about 277.8198892007.

Adding to 21443220 its reverse (2234412), we get a palindrome (23677632).

It can be divided in two parts, 214 and 43220, that added together give a palindrome (43434).

The spelling of 21443220 in words is "twenty-one million, four hundred forty-three thousand, two hundred twenty".