21333231 has 6 divisors (see below), whose sum is σ = 30814680. Its totient is φ = 14222148.

The previous prime is 21333199. The next prime is 21333251. The reversal of 21333231 is 13233312.

It is not a de Polignac number, because 21333231 - 2⁵ = 21333199 is a prime.

It is a super-2 number, since 2×21333231² = 910213489798722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21333251) 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 5 ways as a sum of consecutive naturals, for example, 1185171 + ... + 1185188.

It is an arithmetic number, because the mean of its divisors is an integer number (5135780).

Almost surely, 2^21333231 is an apocalyptic number.

21333231 is a deficient number, since it is larger than the sum of its proper divisors (9481449).

21333231 is a wasteful number, since it uses less digits than its factorization.

21333231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2370365 (or 2370362 counting only the distinct ones).

The product of its digits is 324, while the sum is 18.

The square root of 21333231 is about 4618.7910755954. The cubic root of 21333231 is about 277.3440662772.

Adding to 21333231 its reverse (13233312), we get a palindrome (34566543).

It can be divided in two parts, 213 and 33231, that multiplied together give a triangular number (7078203 = T₃₇₆₂).

The spelling of 21333231 in words is "twenty-one million, three hundred thirty-three thousand, two hundred thirty-one".