21351323 has 8 divisors (see below), whose sum is σ = 24430560. Its totient is φ = 18279360.

The previous prime is 21351311. The next prime is 21351347. The reversal of 21351323 is 32315312.

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 21351323 - 2²⁰ = 20302747 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21351295 and 21351304.

It is not an unprimeable number, because it can be changed into a prime (21351353) 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, 8093 + ... + 10401.

It is an arithmetic number, because the mean of its divisors is an integer number (3053820).

Almost surely, 2^21351323 is an apocalyptic number.

21351323 is a deficient number, since it is larger than the sum of its proper divisors (3079237).

21351323 is a wasteful number, since it uses less digits than its factorization.

21351323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3637.

The product of its digits is 540, while the sum is 20.

The square root of 21351323 is about 4620.7491816804. The cubic root of 21351323 is about 277.4224462011.

Adding to 21351323 its reverse (32315312), we get a palindrome (53666635).

The spelling of 21351323 in words is "twenty-one million, three hundred fifty-one thousand, three hundred twenty-three".