21868533 has 12 divisors (see below), whose sum is σ = 31631340. Its totient is φ = 14558976.

The previous prime is 21868529. The next prime is 21868571. The reversal of 21868533 is 33586812.

It can be written as a sum of positive squares in 2 ways, for example, as 15350724 + 6517809 = 3918^2 + 2553^2 .

It is not a de Polignac number, because 21868533 - 2² = 21868529 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21868573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8485 + ... + 10757.

It is an arithmetic number, because the mean of its divisors is an integer number (2635945).

Almost surely, 2^21868533 is an apocalyptic number.

It is an amenable number.

21868533 is a deficient number, since it is larger than the sum of its proper divisors (9762807).

21868533 is a wasteful number, since it uses less digits than its factorization.

21868533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3348 (or 3345 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 21868533 is about 4676.3803309825. The cubic root of 21868533 is about 279.6446725701.

The spelling of 21868533 in words is "twenty-one million, eight hundred sixty-eight thousand, five hundred thirty-three".