21203240 has 64 divisors (see below), whose sum is σ = 52444800. Its totient is φ = 7679232.

The previous prime is 21203219. The next prime is 21203249. The reversal of 21203240 is 4230212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203249) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16874 + ... + 18086.

It is an arithmetic number, because the mean of its divisors is an integer number (819450).

Almost surely, 2^21203240 is an apocalyptic number.

21203240 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 21203240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26222400).

21203240 is an abundant number, since it is smaller than the sum of its proper divisors (31241560).

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

21203240 is a wasteful number, since it uses less digits than its factorization.

21203240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1266 (or 1262 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 21203240 is about 4604.6976013632. The cubic root of 21203240 is about 276.7795993852.

Adding to 21203240 its reverse (4230212), we get a palindrome (25433452).

The spelling of 21203240 in words is "twenty-one million, two hundred three thousand, two hundred forty".