21325824 has 144 divisors (see below), whose sum is σ = 67076100. Its totient is φ = 6488064.

The previous prime is 21325819. The next prime is 21325891. The reversal of 21325824 is 42852312.

It can be written as a sum of positive squares in 2 ways, for example, as 18662400 + 2663424 = 4320^2 + 1632^2 .

It is a tau number, because it is divible by the number of its divisors (144).

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 239572 + ... + 239660.

Almost surely, 2^21325824 is an apocalyptic number.

21325824 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 21325824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33538050).

21325824 is an abundant number, since it is smaller than the sum of its proper divisors (45750276).

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

21325824 is a wasteful number, since it uses less digits than its factorization.

21325824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130 (or 107 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 21325824 is about 4617.9891727894. The cubic root of 21325824 is about 277.3119641655.

The spelling of 21325824 in words is "twenty-one million, three hundred twenty-five thousand, eight hundred twenty-four".