21233121 has 48 divisors (see below), whose sum is σ = 36465408. Its totient is φ = 10886400.

The previous prime is 21233111. The next prime is 21233123. The reversal of 21233121 is 12133212.

It is not a de Polignac number, because 21233121 - 2⁷ = 21232993 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21233121.

It is not an unprimeable number, because it can be changed into a prime (21233123) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 78216 + ... + 78486.

It is an arithmetic number, because the mean of its divisors is an integer number (759696).

Almost surely, 2^21233121 is an apocalyptic number.

21233121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21233121 is a deficient number, since it is larger than the sum of its proper divisors (15232287).

21233121 is a wasteful number, since it uses less digits than its factorization.

21233121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342 (or 335 counting only the distinct ones).

The product of its digits is 72, while the sum is 15.

The square root of 21233121 is about 4607.9410803525. The cubic root of 21233121 is about 276.9095570263.

Adding to 21233121 its reverse (12133212), we get a palindrome (33366333).

Subtracting from 21233121 its reverse (12133212), we obtain a palindrome (9099909).

It can be divided in two parts, 212 and 33121, that added together give a palindrome (33333).

The spelling of 21233121 in words is "twenty-one million, two hundred thirty-three thousand, one hundred twenty-one".