21200440 has 32 divisors (see below), whose sum is σ = 48312000. Its totient is φ = 8371584.

The previous prime is 21200401. The next prime is 21200461. The reversal of 21200440 is 4400212.

It is a self number, because there is not a number n which added to its sum of digits gives 21200440.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 195 + ... + 6514.

It is an arithmetic number, because the mean of its divisors is an integer number (1509750).

Almost surely, 2^21200440 is an apocalyptic number.

21200440 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 21200440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24156000).

21200440 is an abundant number, since it is smaller than the sum of its proper divisors (27111560).

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

21200440 is a wasteful number, since it uses less digits than its factorization.

21200440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6799 (or 6795 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 21200440 is about 4604.3935539873. The cubic root of 21200440 is about 276.7674154455.

Adding to 21200440 its reverse (4400212), we get a palindrome (25600652).

The spelling of 21200440 in words is "twenty-one million, two hundred thousand, four hundred forty".