21231321 has 8 divisors (see below), whose sum is σ = 28348320. Its totient is φ = 14134272.

The previous prime is 21231313. The next prime is 21231359. The reversal of 21231321 is 12313212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21231321 - 2³ = 21231313 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21231321.

It is not an unprimeable number, because it can be changed into a prime (21231391) 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, 2295 + ... + 6908.

It is an arithmetic number, because the mean of its divisors is an integer number (3543540).

Almost surely, 2^21231321 is an apocalyptic number.

It is an amenable number.

21231321 is a deficient number, since it is larger than the sum of its proper divisors (7116999).

21231321 is an equidigital number, since it uses as much as digits as its factorization.

21231321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9975.

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

The square root of 21231321 is about 4607.7457612156. The cubic root of 21231321 is about 276.9017319671.

Adding to 21231321 its reverse (12313212), we get a palindrome (33544533).

It can be divided in two parts, 2 and 1231321, that multiplied together give a palindrome (2462642).

The spelling of 21231321 in words is "twenty-one million, two hundred thirty-one thousand, three hundred twenty-one".