21305024 has 56 divisors (see below), whose sum is σ = 47152560. Its totient is φ = 9483264.

The previous prime is 21305003. The next prime is 21305027. The reversal of 21305024 is 42050312.

It is a junction number, because it is equal to n+sod(n) for n = 21304993 and 21305011.

It is not an unprimeable number, because it can be changed into a prime (21305027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23687 + ... + 24569.

It is an arithmetic number, because the mean of its divisors is an integer number (842010).

Almost surely, 2^21305024 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 21305024, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23576280).

21305024 is an abundant number, since it is smaller than the sum of its proper divisors (25847536).

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

21305024 is a wasteful number, since it uses less digits than its factorization.

21305024 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 937 (or 927 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21305024 is about 4615.7365609402. The cubic root of 21305024 is about 277.2217767139.

Adding to 21305024 its reverse (42050312), we get a palindrome (63355336).

The spelling of 21305024 in words is "twenty-one million, three hundred five thousand, twenty-four".