21724832 has 12 divisors (see below), whose sum is σ = 42770826. Its totient is φ = 10862400.

The previous prime is 21724819. The next prime is 21724841. The reversal of 21724832 is 23842712.

It can be written as a sum of positive squares in only one way, i.e., 14776336 + 6948496 = 3844^2 + 2636^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21724795 and 21724804.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339419 + ... + 339482.

Almost surely, 2^21724832 is an apocalyptic number.

It is an amenable number.

21724832 is a deficient number, since it is larger than the sum of its proper divisors (21045994).

21724832 is an equidigital number, since it uses as much as digits as its factorization.

21724832 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 678911 (or 678903 counting only the distinct ones).

The product of its digits is 5376, while the sum is 29.

The square root of 21724832 is about 4660.9904526828. The cubic root of 21724832 is about 279.0307987052.

The spelling of 21724832 in words is "twenty-one million, seven hundred twenty-four thousand, eight hundred thirty-two".