21523323 has 4 divisors (see below), whose sum is σ = 28697768. Its totient is φ = 14348880.

The previous prime is 21523283. The next prime is 21523339. The reversal of 21523323 is 32332512.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21523323 - 2¹² = 21519227 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21523323.

It is not an unprimeable number, because it can be changed into a prime (21521323) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3587218 + ... + 3587223.

It is an arithmetic number, because the mean of its divisors is an integer number (7174442).

Almost surely, 2^21523323 is an apocalyptic number.

21523323 is a deficient number, since it is larger than the sum of its proper divisors (7174445).

21523323 is an equidigital number, since it uses as much as digits as its factorization.

21523323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7174444.

The product of its digits is 1080, while the sum is 21.

The square root of 21523323 is about 4639.3235498292. The cubic root of 21523323 is about 278.1653993917.

Adding to 21523323 its reverse (32332512), we get a palindrome (53855835).

The spelling of 21523323 in words is "twenty-one million, five hundred twenty-three thousand, three hundred twenty-three".