21648420 has 72 divisors (see below), whose sum is σ = 66253824. Its totient is φ = 5721408.

The previous prime is 21648401. The next prime is 21648421. The reversal of 21648420 is 2484612.

It is not an unprimeable number, because it can be changed into a prime (21648421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22387 + ... + 23333.

It is an arithmetic number, because the mean of its divisors is an integer number (920192).

Almost surely, 2^21648420 is an apocalyptic number.

21648420 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 21648420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33126912).

21648420 is an abundant number, since it is smaller than the sum of its proper divisors (44605404).

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

21648420 is a wasteful number, since it uses less digits than its factorization.

21648420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1089 (or 1084 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 21648420 is about 4652.7862620155. The cubic root of 21648420 is about 278.7032726141.

The spelling of 21648420 in words is "twenty-one million, six hundred forty-eight thousand, four hundred twenty".