21133231 has 8 divisors (see below), whose sum is σ = 24387584. Its totient is φ = 17937720.

The previous prime is 21133219. The next prime is 21133237. The reversal of 21133231 is 13233112.

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 21133231 - 2⁹ = 21132719 is a prime.

It is a super-2 number, since 2×21133231² = 893226904998722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21133237) 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, 13935 + ... + 15376.

It is an arithmetic number, because the mean of its divisors is an integer number (3048448).

Almost surely, 2^21133231 is an apocalyptic number.

21133231 is a deficient number, since it is larger than the sum of its proper divisors (3254353).

21133231 is a wasteful number, since it uses less digits than its factorization.

21133231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29421.

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

The square root of 21133231 is about 4597.0894052650. The cubic root of 21133231 is about 276.4746392531.

Adding to 21133231 its reverse (13233112), we get a palindrome (34366343).

The spelling of 21133231 in words is "twenty-one million, one hundred thirty-three thousand, two hundred thirty-one".