21685533 has 16 divisors (see below), whose sum is σ = 30481920. Its totient is φ = 13692224.

The previous prime is 21685519. The next prime is 21685549. The reversal of 21685533 is 33558612.

It is a cyclic number.

It is not a de Polignac number, because 21685533 - 2⁸ = 21685277 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21685494 and 21685503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21685513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2260 + ... + 6962.

It is an arithmetic number, because the mean of its divisors is an integer number (1905120).

Almost surely, 2^21685533 is an apocalyptic number.

It is an amenable number.

21685533 is a deficient number, since it is larger than the sum of its proper divisors (8796387).

21685533 is a wasteful number, since it uses less digits than its factorization.

21685533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4788.

The product of its digits is 21600, while the sum is 33.

The square root of 21685533 is about 4656.7728095753. The cubic root of 21685533 is about 278.8624468075.

The spelling of 21685533 in words is "twenty-one million, six hundred eighty-five thousand, five hundred thirty-three".