21528533 has 8 divisors (see below), whose sum is σ = 23247000. Its totient is φ = 19819008.

The previous prime is 21528517. The next prime is 21528553. The reversal of 21528533 is 33582512.

It can be written as a sum of positive squares in 4 ways, for example, as 1965604 + 19562929 = 1402^2 + 4423^2 .

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 21528533 - 2⁴ = 21528517 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21528496 and 21528505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21528553) 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, 3293 + ... + 7341.

It is an arithmetic number, because the mean of its divisors is an integer number (2905875).

Almost surely, 2^21528533 is an apocalyptic number.

It is an amenable number.

21528533 is a deficient number, since it is larger than the sum of its proper divisors (1718467).

21528533 is a wasteful number, since it uses less digits than its factorization.

21528533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4471.

The product of its digits is 7200, while the sum is 29.

The square root of 21528533 is about 4639.8850201271. The cubic root of 21528533 is about 278.1878420974.

The spelling of 21528533 in words is "twenty-one million, five hundred twenty-eight thousand, five hundred thirty-three".