21440232 has 144 divisors (see below), whose sum is σ = 67223520. Its totient is φ = 6156480.

The previous prime is 21440207. The next prime is 21440233. The reversal of 21440232 is 23204412.

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

It is a zygodrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21440233) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 200323 + ... + 200429.

It is an arithmetic number, because the mean of its divisors is an integer number (466830).

Almost surely, 2^21440232 is an apocalyptic number.

21440232 is a gapful number since it is divisible by the number (22) 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 21440232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33611760).

21440232 is an abundant number, since it is smaller than the sum of its proper divisors (45783288).

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

21440232 is a wasteful number, since it uses less digits than its factorization.

21440232 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164 (or 146 counting only the distinct ones).

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

The square root of 21440232 is about 4630.3598132327. The cubic root of 21440232 is about 277.8069843542.

Adding to 21440232 its reverse (23204412), we get a palindrome (44644644).

The spelling of 21440232 in words is "twenty-one million, four hundred forty thousand, two hundred thirty-two".