21435521 has 8 divisors (see below), whose sum is σ = 22737024. Its totient is φ = 20138560.

The previous prime is 21435509. The next prime is 21435527. The reversal of 21435521 is 12553412.

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 21435521 - 2¹⁸ = 21173377 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21435527) 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, 16916 + ... + 18138.

It is an arithmetic number, because the mean of its divisors is an integer number (2842128).

Almost surely, 2^21435521 is an apocalyptic number.

It is an amenable number.

21435521 is a deficient number, since it is larger than the sum of its proper divisors (1301503).

21435521 is a wasteful number, since it uses less digits than its factorization.

21435521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2271.

The product of its digits is 1200, while the sum is 23.

The square root of 21435521 is about 4629.8510775186. The cubic root of 21435521 is about 277.7866356227.

Adding to 21435521 its reverse (12553412), we get a palindrome (33988933).

The spelling of 21435521 in words is "twenty-one million, four hundred thirty-five thousand, five hundred twenty-one".