21265824 has 48 divisors (see below), whose sum is σ = 57341088. Its totient is φ = 6895872.

The previous prime is 21265819. The next prime is 21265831. The reversal of 21265824 is 42856212.

It is a tau number, because it is divible by the number of its divisors (48).

It is a junction number, because it is equal to n+sod(n) for n = 21265791 and 21265800.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 559 + ... + 6545.

It is an arithmetic number, because the mean of its divisors is an integer number (1194606).

Almost surely, 2^21265824 is an apocalyptic number.

21265824 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 21265824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28670544).

21265824 is an abundant number, since it is smaller than the sum of its proper divisors (36075264).

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

21265824 is a wasteful number, since it uses less digits than its factorization.

21265824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6037 (or 6029 counting only the distinct ones).

The product of its digits is 7680, while the sum is 30.

The square root of 21265824 is about 4611.4882630231. The cubic root of 21265824 is about 277.0516483690.

The spelling of 21265824 in words is "twenty-one million, two hundred sixty-five thousand, eight hundred twenty-four".