21312133 has 8 divisors (see below), whose sum is σ = 21876800. Its totient is φ = 20750688.

The previous prime is 21312121. The next prime is 21312149. The reversal of 21312133 is 33121312.

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 21312133 - 2⁹ = 21311621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21312113) 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, 18313 + ... + 19441.

It is an arithmetic number, because the mean of its divisors is an integer number (2734600).

Almost surely, 2^21312133 is an apocalyptic number.

It is an amenable number.

21312133 is a deficient number, since it is larger than the sum of its proper divisors (564667).

21312133 is a wasteful number, since it uses less digits than its factorization.

21312133 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1611.

The product of its digits is 108, while the sum is 16.

The square root of 21312133 is about 4616.5065796552. The cubic root of 21312133 is about 277.2526074771.

Adding to 21312133 its reverse (33121312), we get a palindrome (54433445).

The spelling of 21312133 in words is "twenty-one million, three hundred twelve thousand, one hundred thirty-three".