21504530 has 8 divisors (see below), whose sum is σ = 38708172. Its totient is φ = 8601808.

The previous prime is 21504463. The next prime is 21504533. The reversal of 21504530 is 3540512.

It can be written as a sum of positive squares in 2 ways, for example, as 20967241 + 537289 = 4579^2 + 733^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21504533) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1075217 + ... + 1075236.

Almost surely, 2^21504530 is an apocalyptic number.

21504530 is a deficient number, since it is larger than the sum of its proper divisors (17203642).

21504530 is a wasteful number, since it uses less digits than its factorization.

21504530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2150460.

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 21504530 is about 4637.2977044826. The cubic root of 21504530 is about 278.0844161631.

The spelling of 21504530 in words is "twenty-one million, five hundred four thousand, five hundred thirty".