21531533 has 8 divisors (see below), whose sum is σ = 21843360. Its totient is φ = 21222000.

The previous prime is 21531527. The next prime is 21531599. The reversal of 21531533 is 33513512.

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 21531533 - 2²⁴ = 4754317 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21531499 and 21531508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531233) 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 7 ways as a sum of consecutive naturals, for example, 26966 + ... + 27752.

It is an arithmetic number, because the mean of its divisors is an integer number (2730420).

Almost surely, 2^21531533 is an apocalyptic number.

It is an amenable number.

21531533 is a deficient number, since it is larger than the sum of its proper divisors (311827).

21531533 is a wasteful number, since it uses less digits than its factorization.

21531533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1147.

The product of its digits is 1350, while the sum is 23.

The square root of 21531533 is about 4640.2082927386. The cubic root of 21531533 is about 278.2007633179.

The spelling of 21531533 in words is "twenty-one million, five hundred thirty-one thousand, five hundred thirty-three".