21335521 has 8 divisors (see below), whose sum is σ = 22109760. Its totient is φ = 20575152.

The previous prime is 21335519. The next prime is 21335549. The reversal of 21335521 is 12553312.

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

It is a cyclic number.

It is not a de Polignac number, because 21335521 - 2¹ = 21335519 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21335492 and 21335501.

It is not an unprimeable number, because it can be changed into a prime (21335581) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 285 + ... + 6538.

It is an arithmetic number, because the mean of its divisors is an integer number (2763720).

Almost surely, 2^21335521 is an apocalyptic number.

It is an amenable number.

21335521 is a deficient number, since it is larger than the sum of its proper divisors (774239).

21335521 is an equidigital number, since it uses as much as digits as its factorization.

21335521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6935.

The product of its digits is 900, while the sum is 22.

The square root of 21335521 is about 4619.0389693095. The cubic root of 21335521 is about 277.3539896871.

Adding to 21335521 its reverse (12553312), we get a palindrome (33888833).

The spelling of 21335521 in words is "twenty-one million, three hundred thirty-five thousand, five hundred twenty-one".