21612323 has 4 divisors (see below), whose sum is σ = 21682128. Its totient is φ = 21542520.

The previous prime is 21612319. The next prime is 21612373. The reversal of 21612323 is 32321612.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21612323 - 2² = 21612319 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21612295 and 21612304.

It is not an unprimeable number, because it can be changed into a prime (21612313) 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, 34436 + ... + 35057.

It is an arithmetic number, because the mean of its divisors is an integer number (5420532).

Almost surely, 2^21612323 is an apocalyptic number.

21612323 is a deficient number, since it is larger than the sum of its proper divisors (69805).

21612323 is an equidigital number, since it uses as much as digits as its factorization.

21612323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69804.

The product of its digits is 432, while the sum is 20.

The square root of 21612323 is about 4648.9055701315. The cubic root of 21612323 is about 278.5482813364.

Adding to 21612323 its reverse (32321612), we get a palindrome (53933935).

The spelling of 21612323 in words is "twenty-one million, six hundred twelve thousand, three hundred twenty-three".