21309323 has 8 divisors (see below), whose sum is σ = 24481248. Its totient is φ = 18169344.

The previous prime is 21309319. The next prime is 21309331. The reversal of 21309323 is 32390312.

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 21309323 - 2² = 21309319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21309383) 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, 6536 + ... + 9237.

It is an arithmetic number, because the mean of its divisors is an integer number (3060156).

Almost surely, 2^21309323 is an apocalyptic number.

21309323 is a deficient number, since it is larger than the sum of its proper divisors (3171925).

21309323 is a wasteful number, since it uses less digits than its factorization.

21309323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15973.

The product of its (nonzero) digits is 972, while the sum is 23.

The square root of 21309323 is about 4616.2022269394. The cubic root of 21309323 is about 277.2404217099.

Adding to 21309323 its reverse (32390312), we get a palindrome (53699635).

The spelling of 21309323 in words is "twenty-one million, three hundred nine thousand, three hundred twenty-three".