21072384 has 120 divisors (see below), whose sum is σ = 64633140. Its totient is φ = 6586368.

The previous prime is 21072379. The next prime is 21072407. The reversal of 21072384 is 48327012.

21072384 is a `hidden beast` number, since 210 + 72 + 384 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 20793600 + 278784 = 4560^2 + 528^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 78202 + ... + 78470.

Almost surely, 2^21072384 is an apocalyptic number.

21072384 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 21072384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32316570).

21072384 is an abundant number, since it is smaller than the sum of its proper divisors (43560756).

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

21072384 is a wasteful number, since it uses less digits than its factorization.

21072384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310 (or 291 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21072384 is about 4590.4666429460. The cubic root of 21072384 is about 276.2090413808.

Adding to 21072384 its reverse (48327012), we get a palindrome (69399396).

The spelling of 21072384 in words is "twenty-one million, seventy-two thousand, three hundred eighty-four".