21368833 has 4 divisors (see below), whose sum is σ = 21432580. Its totient is φ = 21305088.

The previous prime is 21368821. The next prime is 21368843. The reversal of 21368833 is 33886312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3323329 + 18045504 = 1823^2 + 4248^2 .

It is a cyclic number.

It is not a de Polignac number, because 21368833 - 2⁵ = 21368801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21368803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31368 + ... + 32041.

It is an arithmetic number, because the mean of its divisors is an integer number (5358145).

Almost surely, 2^21368833 is an apocalyptic number.

It is an amenable number.

21368833 is a deficient number, since it is larger than the sum of its proper divisors (63747).

21368833 is an equidigital number, since it uses as much as digits as its factorization.

21368833 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63746.

The product of its digits is 20736, while the sum is 34.

The square root of 21368833 is about 4622.6435077778. The cubic root of 21368833 is about 277.4982625760.

It can be divided in two parts, 21368 and 833, that added together give a square (22201 = 149²).

The spelling of 21368833 in words is "twenty-one million, three hundred sixty-eight thousand, eight hundred thirty-three".