21648900 has 216 divisors, whose sum is σ = 78786624. Its totient is φ = 4492800.

The previous prime is 21648889. The next prime is 21648901. The reversal of 21648900 is 984612.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21648901) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 354870 + ... + 354930.

Almost surely, 2^21648900 is an apocalyptic number.

21648900 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 21648900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39393312).

21648900 is an abundant number, since it is smaller than the sum of its proper divisors (57137724).

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

21648900 is a wasteful number, since it uses less digits than its factorization.

21648900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111 (or 91 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21648900 is about 4652.8378437251. The cubic root of 21648900 is about 278.7053324501.

The spelling of 21648900 in words is "twenty-one million, six hundred forty-eight thousand, nine hundred".