21039824 has 60 divisors (see below), whose sum is σ = 45747072. Its totient is φ = 9360000.

The previous prime is 21039817. The next prime is 21039853. The reversal of 21039824 is 42893012.

It is a zygodrome in base 13.

It is a congruent number.

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, 83699 + ... + 83949.

Almost surely, 2^21039824 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 21039824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22873536).

21039824 is an abundant number, since it is smaller than the sum of its proper divisors (24707248).

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

21039824 is a wasteful number, since it uses less digits than its factorization.

21039824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316 (or 297 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 21039824 is about 4586.9187915201. The cubic root of 21039824 is about 276.0667065537.

The spelling of 21039824 in words is "twenty-one million, thirty-nine thousand, eight hundred twenty-four".