21648384 has 154 divisors (see below), whose sum is σ = 67121130. Its totient is φ = 6967296.

The previous prime is 21648383. The next prime is 21648401. The reversal of 21648384 is 48384612.

21648384 is a `hidden beast` number, since 2 + 1 + 648 + 3 + 8 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 18662400 + 2985984 = 4320^2 + 1728^2 .

It is a super-2 number, since 2×21648384² = 937305059622912, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21648383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 746482 + ... + 746510.

Almost surely, 2^21648384 is an apocalyptic number.

21648384 is a gapful number since it is divisible by the number (24) 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 21648384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33560565).

21648384 is an abundant number, since it is smaller than the sum of its proper divisors (45472746).

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

21648384 is an frugal number, since it uses more digits than its factorization.

21648384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67 (or 34 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 21648384 is about 4652.7823933642. The cubic root of 21648384 is about 278.7031181252.

The spelling of 21648384 in words is "twenty-one million, six hundred forty-eight thousand, three hundred eighty-four".