21535523 has 4 divisors (see below), whose sum is σ = 21748848. Its totient is φ = 21322200.

The previous prime is 21535513. The next prime is 21535529. The reversal of 21535523 is 32553512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21535523 - 2¹⁴ = 21519139 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21535492 and 21535501.

It is not an unprimeable number, because it can be changed into a prime (21535529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 106511 + ... + 106712.

It is an arithmetic number, because the mean of its divisors is an integer number (5437212).

Almost surely, 2^21535523 is an apocalyptic number.

21535523 is a deficient number, since it is larger than the sum of its proper divisors (213325).

21535523 is a wasteful number, since it uses less digits than its factorization.

21535523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213324.

The product of its digits is 4500, while the sum is 26.

The square root of 21535523 is about 4640.6382104189. The cubic root of 21535523 is about 278.2179466816.

The spelling of 21535523 in words is "twenty-one million, five hundred thirty-five thousand, five hundred twenty-three".