20659521 has 8 divisors (see below), whose sum is σ = 27698944. Its totient is φ = 13696560.

The previous prime is 20659519. The next prime is 20659549. The reversal of 20659521 is 12595602.

It is a happy number.

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

It is not a de Polignac number, because 20659521 - 2¹ = 20659519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20659501) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 18481 + ... + 19566.

It is an arithmetic number, because the mean of its divisors is an integer number (3462368).

Almost surely, 2^20659521 is an apocalyptic number.

It is an amenable number.

20659521 is a deficient number, since it is larger than the sum of its proper divisors (7039423).

20659521 is a wasteful number, since it uses less digits than its factorization.

20659521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38231.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 20659521 is about 4545.2745791646. The cubic root of 20659521 is about 274.3932451723.

The spelling of 20659521 in words is "twenty million, six hundred fifty-nine thousand, five hundred twenty-one".