21241440 has 240 divisors, whose sum is σ = 82328400. Its totient is φ = 5114880.

The previous prime is 21241433. The next prime is 21241453. The reversal of 21241440 is 4414212.

21241440 is a `hidden beast` number, since 212 + 414 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-3 number, since 3×21241440³ (a number of 23 digits) contains 333 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 142486 + ... + 142634.

It is an arithmetic number, because the mean of its divisors is an integer number (343035).

Almost surely, 2^21241440 is an apocalyptic number.

21241440 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 21241440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41164200).

21241440 is an abundant number, since it is smaller than the sum of its proper divisors (61086960).

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

21241440 is a wasteful number, since it uses less digits than its factorization.

21241440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 21241440 is about 4608.8436727665. The cubic root of 21241440 is about 276.9457160979.

Adding to 21241440 its reverse (4414212), we get a palindrome (25655652).

The spelling of 21241440 in words is "twenty-one million, two hundred forty-one thousand, four hundred forty".