21001323 has 16 divisors (see below), whose sum is σ = 33394176. Its totient is φ = 11478720.

The previous prime is 21001319. The next prime is 21001349. The reversal of 21001323 is 32310012.

It is a happy number.

It is not a de Polignac number, because 21001323 - 2² = 21001319 is a prime.

21001323 is a modest number, since divided by 1323 gives 21 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 21001299 and 21001308.

It is not an unprimeable number, because it can be changed into a prime (21001523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21258 + ... + 22223.

It is an arithmetic number, because the mean of its divisors is an integer number (2087136).

Almost surely, 2^21001323 is an apocalyptic number.

21001323 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21001323 is a deficient number, since it is larger than the sum of its proper divisors (12392853).

21001323 is a wasteful number, since it uses less digits than its factorization.

21001323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43514.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21001323 is about 4582.7200438168. The cubic root of 21001323 is about 275.8982112572.

Adding to 21001323 its reverse (32310012), we get a palindrome (53311335).

The spelling of 21001323 in words is "twenty-one million, one thousand, three hundred twenty-three".