21200240 has 20 divisors (see below), whose sum is σ = 49290744. Its totient is φ = 8480064.

The previous prime is 21200233. The next prime is 21200279. The reversal of 21200240 is 4200212.

It is a tau number, because it is divible by the number of its divisors (20).

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 3 ways as a sum of consecutive naturals, for example, 132422 + ... + 132581.

Almost surely, 2^21200240 is an apocalyptic number.

21200240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21200240 is an abundant number, since it is smaller than the sum of its proper divisors (28090504).

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

21200240 is a wasteful number, since it uses less digits than its factorization.

21200240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265016 (or 265010 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21200240 is about 4604.3718355493. The cubic root of 21200240 is about 276.7665451231.

Adding to 21200240 its reverse (4200212), we get a palindrome (25400452).

The spelling of 21200240 in words is "twenty-one million, two hundred thousand, two hundred forty".