21840648 has 64 divisors (see below), whose sum is σ = 58320000. Its totient is φ = 6792192.

The previous prime is 21840641. The next prime is 21840667. The reversal of 21840648 is 84604812.

It is a super-3 number, since 3×21840648³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21840641) 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, 81058 + ... + 81326.

It is an arithmetic number, because the mean of its divisors is an integer number (911250).

Almost surely, 2^21840648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21840648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29160000).

21840648 is an abundant number, since it is smaller than the sum of its proper divisors (36479352).

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

21840648 is a wasteful number, since it uses less digits than its factorization.

21840648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494 (or 490 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 33.

The square root of 21840648 is about 4673.3979073047. The cubic root of 21840648 is about 279.5257618586.

The spelling of 21840648 in words is "twenty-one million, eight hundred forty thousand, six hundred forty-eight".